Mypy type correctness (#3199)

51 files changed, 577 insertions, 302 deletions

diff --git a/.github/mypy-github-formatter b/.github/mypy-github-formatter
new file mode 100755
index 00000000..dfc8309a
--- /dev/null
+++ b/.github/mypy-github-formatter
@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+
+# A helper script that you can pipe the output of `mypy --output json` into Github actions workflow message commands
+# so they show up in the code review panel and job output as warnings.
+# (https://docs.github.com/en/actions/writing-workflows/choosing-what-your-workflow-does/workflow-commands-for-github-actions#about-workflow-commands)
+
+import json
+
+had_errors = False
+
+while True:
+    try:
+        line = input()
+    except EOFError:
+        break
+    if len(line) == 0:
+        break
+
+    had_errors = True
+    
+    line = json.loads(line)
+
+    # Format the line into a github command that will show up in the code review panel,
+    # as well as a note about the file and line so that it's clear to readers of the build log where
+    # errors were found
+
+    # Could use line["severity"] to change the message type, but for now we just
+    # want to use these to flag potential commit issues rather than reject commits outright.
+    github_out = '::warning title=Type Checking,file={file},line={line},col={column}::{message} [{code}]'.format(**line)
+    hint = line["hint"]
+    if hint is not None:
+        github_out += f". HINT: {hint}"
+
+    print(github_out)
+    print('(in {file}:{line})'.format(**line))
+
+if not had_errors:
+    print("No type errors found!")
\ No newline at end of file
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 7ecbffbb..de20b889 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -66,9 +66,16 @@ jobs:
       - shell: bash
         run: |
           bin/build-linux
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
@@ -131,9 +138,16 @@ jobs:
           python -m pip install pyinstaller
 
           echo "${{ env.pythonLocation }}\bin" >> $GITHUB_PATH
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
@@ -286,9 +300,16 @@ jobs:
         run: |
           SET BUILD32="1"
           bin\build-geos-win.cmd
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
@@ -345,9 +366,16 @@ jobs:
         shell: cmd
         run: |
           bin\build-geos-win.cmd
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
@@ -404,9 +432,16 @@ jobs:
           pip install pyinstaller
 
           echo "${{ env.pythonLocation }}/bin" >> $GITHUB_PATH
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
@@ -466,9 +501,16 @@ jobs:
           pip install pyinstaller
 
           echo "${{ env.pythonLocation }}/bin" >> $GITHUB_PATH
-      - shell: bash
+      - name: Tests
+        shell: bash
         run: |
           pytest
+      - name: Mypy Type Checking
+        shell: bash
+        run: |
+          python -m pip install mypy
+          python -m mypy --output json | python .github/mypy-github-formatter
+        continue-on-error: true
       - shell: bash
         run: |
           make dist
diff --git a/CODING_STYLE.md b/CODING_STYLE.md
index 34fff7c4..39fa5244 100644
--- a/CODING_STYLE.md
+++ b/CODING_STYLE.md
@@ -31,6 +31,32 @@ if [ "$?" != "0" ]; then
 fi
 ```
 
+Type Annotations
+================
+
+We encourage the use of type annotations in Python code. 
+Type annotations make the code easier to read and understand, for example by making it clear what kinds of data functions accept as arguments and return.
+Editors and IDEs can also read this type information to power features like autocomplete.
+Type annotations also allow us to use the typechecker [Mypy](https://mypy.readthedocs.io/en/stable/#) to check for errors.
+
+A great reference for how to use annotations is the [Mypy cheat sheet](https://mypy.readthedocs.io/en/stable/cheat_sheet_py3.html).
+It covers most of the common uses and patterns.
+[Mypy's Common Issues page](https://mypy.readthedocs.io/en/stable/common_issues.html) is also useful for understanding the common pitfalls with type-checking you may encounter.
+Notably, Mypy does not perform type-checking on functions that don't have type annotations, but as we introduce new code with annotations we'll have better coverage as time goes on.
+
+You can run Mypy against your changes yourself simply by [installing Mypy](https://mypy.readthedocs.io/en/stable/getting_started.html#installing-and-running-mypy) running `mypy` in the project root.
+The project's mypy.ini file sets all of the relevant configuration, so no other arguments are needed.
+Mypy is also run as part of this project's builds on Github.
+Errors that Mypy picks up won't cause your build to fail, but will appear on Pull Requests so both you and reviewers can see the potential issues.
+
+Much of our code, especially older code, lacks type annotations.
+If you want to add type annotations to older code, or learn what types are used in a part of the codebase without type annotations, you my find [MonkeyType](https://monkeytype.readthedocs.io/en/stable/) useful.
+You can easily have MonkeyType collect type information from Ink/Stitch in a similar way to how you can use one of several profilers with Ink/Stitch.
+Simply copy `DEBUG_template.toml` to `DEBUG.toml`, and uncomment lines so that the `profiler_type = "monkeytype"`
+and `profile_enable = True` options are set.
+After running Ink/Stitch command, a window will pop up telling you how to run Monkeytype and use your newly-collected type information.
+Multiple command runs will all add to the type information database.
+
 Guidance and Comments
 =====================
 
diff --git a/DEBUG_template.toml b/DEBUG_template.toml
index f446b98d..f33b17b7 100644
--- a/DEBUG_template.toml
+++ b/DEBUG_template.toml
@@ -45,6 +45,7 @@
 # profiler_type = "cprofile"
 # profiler_type = "profile"
 # profiler_type = "pyinstrument"
+# profiler_type = "monkeytype"
 
 ### enable profiler, see cmd line arg -p, default: false
 # profile_enable = true
diff --git a/lib/commands.py b/lib/commands.py
index c1ac35a0..abef3912 100644
--- a/lib/commands.py
+++ b/lib/commands.py
@@ -7,7 +7,7 @@ import os
 import sys
 from copy import deepcopy
 from random import random
-from typing import List
+from typing import List, Optional, cast
 
 import inkex
 from shapely import geometry as shgeo
@@ -110,17 +110,17 @@ class BaseCommand(object):
 
 
 class Command(BaseCommand):
-    def __init__(self, connector):
-        self.connector: inkex.Path = connector
+    def __init__(self, connector: inkex.PathElement) -> None:
+        self.connector = connector
         self.svg = self.connector.getroottree().getroot()
 
         self.parse_command()
 
-    def parse_connector_path(self):
+    def parse_connector_path(self) -> inkex.Path:
         path = inkex.paths.Path(self.connector.get('d')).to_superpath()
         return apply_transforms(path, self.connector)
 
-    def parse_command(self):
+    def parse_command(self) -> None:
         path = self.parse_connector_path()
         if len(path) == 0:
             raise CommandParseError("connector has no path information")
@@ -144,7 +144,7 @@ class Command(BaseCommand):
 
         self.target: inkex.BaseElement = neighbors[1]
 
-        pos = [float(self.use.get("x", 0)), float(self.use.get("y", 0))]
+        pos = (float(self.use.get("x", 0)), float(self.use.get("y", 0)))
         transform = get_node_transform(self.use)
         pos = inkex.Transform(transform).apply_to_point(pos)
         self.target_point = pos
@@ -156,13 +156,16 @@ class Command(BaseCommand):
         """
         Clone this command and point it to the new target, positioning it relative to the new target the same as the target
         """
-        group: inkex.BaseElement = self.connector.getparent()
-        transform_relative_to_target = -self.target.composed_transform() @ group.composed_transform()
+        group: Optional[inkex.BaseElement] = cast(Optional[inkex.BaseElement], self.connector.getparent())
+        assert group is not None, "The connector should be part of a group."
+        transform_relative_to_target: inkex.Transform = -self.target.composed_transform() @ group.composed_transform()
 
         # Clone group
-        cloned_group = copy_no_children(self.connector.getparent())
+        cloned_group = copy_no_children(group)
         cloned_group.transform = new_target.transform @ transform_relative_to_target
-        new_target.getparent().append(cloned_group)
+        new_target_parent = new_target.getparent()
+        assert new_target_parent is not None, "The target should be a non-root element."
+        new_target_parent.append(cloned_group)
 
         symbol = copy_no_children(self.use)
         cloned_group.append(symbol)
@@ -200,12 +203,11 @@ class StandaloneCommand(BaseCommand):
 
     @property
     @cache
-    def point(self):
-        pos = [float(self.node.get("x", 0)), float(self.node.get("y", 0))]
+    def point(self) -> Point:
+        pos = (float(self.node.get("x", 0)), float(self.node.get("y", 0)))
         transform = get_node_transform(self.node)
-        pos = inkex.transforms.Transform(transform).apply_to_point(pos)
 
-        return Point(*pos)
+        return Point(*inkex.transforms.Transform(transform).apply_to_point(pos))
 
 
 def get_command_description(command: str) -> str:
@@ -298,11 +300,11 @@ def _standalone_commands(svg):
             pass
 
 
-def is_command(node):
+def is_command(node: inkex.BaseElement) -> bool:
     return CONNECTION_START in node.attrib or CONNECTION_END in node.attrib
 
 
-def is_command_symbol(node):
+def is_command_symbol(node: inkex.BaseElement) -> bool:
     symbol = None
     xlink = node.get(XLINK_HREF, "")
     if xlink.startswith("#inkstitch_"):
@@ -311,23 +313,23 @@ def is_command_symbol(node):
 
 
 @cache
-def symbols_path():
+def symbols_path() -> str:
     return os.path.join(get_bundled_dir("symbols"), "inkstitch.svg")
 
 
 @cache
-def symbols_svg():
+def symbols_svg() -> inkex.BaseElement:
     with open(symbols_path()) as symbols_file:
         return inkex.load_svg(symbols_file).getroot()
 
 
 @cache
-def symbol_defs():
+def symbol_defs() -> inkex.BaseElement:
     return symbols_svg().defs
 
 
 @cache
-def ensure_symbol(svg, command):
+def ensure_symbol(svg, command) -> None:
     """Make sure the command's symbol definition exists in the <svg:defs> tag."""
 
     # using @cache really just makes sure that we don't bother ensuring the
diff --git a/lib/debug/debugger.py b/lib/debug/debugger.py
index 11293c8a..c58ddb3e 100644
--- a/lib/debug/debugger.py
+++ b/lib/debug/debugger.py
@@ -125,6 +125,10 @@
 #   to see flask server url routes:
 #      - comment out the line self.disable_logging() in run() of lib/api/server.py
 
+# We have some ignores so you don't see errors if you don't have one or more of the debugger libraries installed.
+# But in turn those ignores will cause unused-ignore errors if those libraries aren't installed...
+# mypy: disable-error-code="unused-ignore"
+
 import os
 import sys
 
@@ -148,11 +152,11 @@ def init_debugger(debug_type:str,  ini: dict):
 
     try:
         if debugger == 'vscode':
-            import debugpy
+            import debugpy  # type: ignore[import-untyped, import-not-found]
         elif debugger == 'pycharm':
-            import pydevd_pycharm
+            import pydevd_pycharm  # type: ignore[import-untyped, import-not-found]
         elif debugger == 'pydev':
-            import pydevd
+            import pydevd  # type: ignore[import-untyped, import-not-found]
         elif debugger == 'file':
             pass
         else:
diff --git a/lib/debug/logging.py b/lib/debug/logging.py
index fa474348..c46140ec 100644
--- a/lib/debug/logging.py
+++ b/lib/debug/logging.py
@@ -69,6 +69,7 @@
 import os
 import sys
 from pathlib import Path
+from typing import Dict, Any
 
 if sys.version_info >= (3, 11):
     import tomllib      # built-in in Python 3.11+
@@ -139,7 +140,7 @@ def disable_warnings():
 # in development mode we want to use configuration from some LOGGING.toml file
 def activate_for_development(ini: dict, SCRIPTDIR: Path):
     logging_config_file = safe_get(ini, "LOGGING", "log_config_file", default=None)
-    vars = {'SCRIPTDIR': SCRIPTDIR}        # dynamic data for logging configuration
+    vars: Dict[str, Any] = {'SCRIPTDIR': SCRIPTDIR}        # dynamic data for logging configuration
 
     if logging_config_file is not None:
         logging_config_file = Path(logging_config_file)
@@ -157,7 +158,7 @@ def activate_for_development(ini: dict, SCRIPTDIR: Path):
 
     logger.info("Running in development mode")
     logger.info(f"Using logging configuration from file: {logging_config_file}")
-    logger.debug(f"Logging configuration: {devel_config = }")
+    logger.debug(f"Logging configuration: {devel_config=}")
 
 
 # --------------------------------------------------------------------------------------------
@@ -177,7 +178,7 @@ def configure_logging(config: dict, ini: dict, vars: dict):
 
     disable_logging = safe_get(ini, "LOGGING", "disable_logging", default=False)
     if disable_logging:
-        logger.warning(f"Logging is disabled by configuration in ini file. {disable_logging = }")
+        logger.warning(f"Logging is disabled by configuration in ini file. {disable_logging=}")
         logging.disable()  # globally disable all logging of all loggers
 
 
diff --git a/lib/debug/utils.py b/lib/debug/utils.py
index 10d840d9..a758ab3b 100644
--- a/lib/debug/utils.py
+++ b/lib/debug/utils.py
@@ -14,6 +14,10 @@ import logging
 
 logger = logging.getLogger("inkstitch")
 
+# We have some ignores so you don't see errors if you don't have one or more of the profiling libraries installed.
+# But in turn those ignores will cause unused-ignore errors if those libraries aren't installed...
+# mypy: disable-error-code="unused-ignore"
+
 
 # safe_get - get value from nested dictionary, return default if key does not exist
 # - to read nested values from dict - mimic get method of dict with default value
@@ -67,7 +71,7 @@ def write_offline_debug_script(debug_script_dir: Path, ini: dict):
 
         # environment PATH
         f.write('# PATH:\n')
-        f.write(f'#   {os.environ.get("PATH","")}\n')
+        f.write(f'#   {os.environ.get("PATH", "")}\n')
         # for p in os.environ.get("PATH", '').split(os.pathsep): # PATH to list
         #     f.write(f'#   {p}\n')
 
@@ -217,6 +221,8 @@ def profile(profiler_type, profile_dir: Path, ini: dict, extension, remaining_ar
         with_profile(extension, remaining_args, profile_file_path)
     elif profiler_type == 'pyinstrument':
         with_pyinstrument(extension, remaining_args, profile_file_path)
+    elif profiler_type == 'monkeytype':
+        with_monkeytype(extension, remaining_args, profile_file_path)
     else:
         raise ValueError(f"unknown profiler type: '{profiler_type}'")
 
@@ -265,7 +271,7 @@ def with_pyinstrument(extension, remaining_args, profile_file_path: Path):
     '''
     profile with pyinstrument
     '''
-    import pyinstrument
+    import pyinstrument  # type: ignore[import-untyped,import-not-found]
     profiler = pyinstrument.Profiler()
 
     profiler.start()
@@ -276,3 +282,25 @@ def with_pyinstrument(extension, remaining_args, profile_file_path: Path):
     with open(profile_file_path, 'w') as stats_file:
         stats_file.write(profiler.output_html())
     print(f"Profiler: pyinstrument, stats written to '{profile_file_path.name}'. Use browser to see it.", file=sys.stderr)
+
+
+def with_monkeytype(extension, remaining_args, profile_file_path: Path) -> None:
+    '''
+    'profile' with monkeytype to get type information. This may be handy for anyone who wants to
+    add type annotations to older parts of our code that don't have them.
+
+    See https://monkeytype.readthedocs.io/en/stable/generation.html for usage instructions.
+    '''
+    import monkeytype  # type: ignore[import-not-found]
+
+    # Monkeytype will use these environment variables for the db path and to filter the modules respectively.
+    # This is easier than using monkeytype's actual config API, anyway.
+    dbpath = profile_file_path.with_suffix('.sqlite')
+    os.environ["MT_DB_PATH"] = str(dbpath)
+    os.environ["MONKEYTYPE_TRACE_MODULES"] = str(Path(__file__).parents[2].name)
+
+    with monkeytype.trace():
+        extension.run(args=remaining_args)
+
+    print(f"Profiler: monkeytype, db written to '{dbpath}'.\n\n" +
+          f"Run 'MT_DB_PATH={dbpath} monkeytype ...' from the inkstitch repo directory.", file=sys.stderr)
diff --git a/lib/elements/clone.py b/lib/elements/clone.py
index 943428b8..9c3e3e3a 100644
--- a/lib/elements/clone.py
+++ b/lib/elements/clone.py
@@ -5,11 +5,11 @@
 
 from contextlib import contextmanager
 from math import degrees
-from typing import Dict, Generator, List
+from typing import Dict, Generator, List, Optional, Tuple, Any, cast
 
-from inkex import BaseElement, Title, Transform
+from inkex import BaseElement, Title, Transform, Vector2d
 from lxml.etree import _Comment
-from shapely import MultiLineString
+from shapely import Geometry, MultiLineString, Point as ShapelyPoint
 
 from ..commands import (find_commands, is_command_symbol,
                         point_command_symbols_up)
@@ -40,12 +40,12 @@ class Clone(EmbroideryElement):
     name = "Clone"
     element_name = _("Clone")
 
-    def __init__(self, *args, **kwargs):
-        super(Clone, self).__init__(*args, **kwargs)
+    def __init__(self, node: BaseElement) -> None:
+        super(Clone, self).__init__(node)
 
     @property
     @param('clone', _("Clone"), type='toggle', inverse=False, default=True)
-    def clone(self):
+    def clone(self) -> bool:
         return self.get_boolean_param("clone", True)
 
     @property
@@ -55,7 +55,7 @@ class Clone(EmbroideryElement):
            unit='deg',
            type='float')
     @cache
-    def clone_fill_angle(self):
+    def clone_fill_angle(self) -> float:
         return self.get_float_param('angle')
 
     @property
@@ -66,15 +66,15 @@ class Clone(EmbroideryElement):
            type='boolean',
            default=False)
     @cache
-    def flip_angle(self):
+    def flip_angle(self) -> bool:
         return self.get_boolean_param('flip_angle', False)
 
-    def get_cache_key_data(self, previous_stitch, next_element):
+    def get_cache_key_data(self, previous_stitch: Any, next_element: EmbroideryElement) -> List[str]:
         source_node = self.node.href
         source_elements = self.clone_to_elements(source_node)
         return [element.get_cache_key(previous_stitch, next_element) for element in source_elements]
 
-    def clone_to_elements(self, node) -> List[EmbroideryElement]:
+    def clone_to_elements(self, node: BaseElement) -> List[EmbroideryElement]:
         # Only used in get_cache_key_data, actual embroidery uses nodes_to_elements+iterate_nodes
         from .utils import node_to_elements
         elements = []
@@ -85,7 +85,7 @@ class Clone(EmbroideryElement):
                 elements.extend(node_to_elements(child, True))
         return elements
 
-    def to_stitch_groups(self, last_stitch_group=None, next_element=None) -> List[StitchGroup]:
+    def to_stitch_groups(self, last_stitch_group: Optional[StitchGroup], next_element: Optional[EmbroideryElement] = None) -> List[StitchGroup]:
         if not self.clone:
             return []
 
@@ -96,7 +96,7 @@ class Clone(EmbroideryElement):
 
             next_elements = [next_element]
             if len(elements) > 1:
-                next_elements = elements[1:] + next_elements
+                next_elements = cast(List[Optional[EmbroideryElement]], elements[1:]) + next_elements
             for element, next_element in zip(elements, next_elements):
                 # Using `embroider` here to get trim/stop after commands, etc.
                 element_stitch_groups = element.embroider(last_stitch_group, next_element)
@@ -107,26 +107,26 @@ class Clone(EmbroideryElement):
             return stitch_groups
 
     @property
-    def first_stitch(self):
+    def first_stitch(self) -> Optional[ShapelyPoint]:
         first, last = self.first_and_last_element()
         if first:
             return first.first_stitch
         return None
 
-    def uses_previous_stitch(self):
+    def uses_previous_stitch(self) -> bool:
         first, last = self.first_and_last_element()
         if first:
             return first.uses_previous_stitch()
-        return None
+        return False
 
-    def uses_next_element(self):
+    def uses_next_element(self) -> bool:
         first, last = self.first_and_last_element()
         if last:
             return last.uses_next_element()
-        return None
+        return False
 
     @cache
-    def first_and_last_element(self):
+    def first_and_last_element(self) -> Tuple[Optional[EmbroideryElement], Optional[EmbroideryElement]]:
         with self.clone_elements() as elements:
             if len(elements):
                 return elements[0], elements[-1]
@@ -153,7 +153,7 @@ class Clone(EmbroideryElement):
             for cloned_node in cloned_nodes:
                 cloned_node.delete()
 
-    def resolve_clone(self, recursive=True) -> List[BaseElement]:
+    def resolve_clone(self, recursive: bool = True) -> List[BaseElement]:
         """
         "Resolve" this clone element by copying the node it hrefs as if unlinking the clone in Inkscape.
         The node will be added as a sibling of this element's node, with its transform and style applied.
@@ -162,9 +162,12 @@ class Clone(EmbroideryElement):
         :param recursive: Recursively "resolve" all child clones in the same manner
         :returns: A list where the first element is the "resolved" node, and zero or more commands attached to that node
         """
-        parent: BaseElement = self.node.getparent()
-        source_node: BaseElement = self.node.href
-        source_parent: BaseElement = source_node.getparent()
+        parent: Optional[BaseElement] = self.node.getparent()
+        assert parent is not None, f"Element {self.node.get_id()} should have a parent"
+        source_node: Optional[BaseElement] = self.node.href
+        assert source_node is not None, f"Target of {self.node.get_id()} was None!"
+        source_parent: Optional[BaseElement] = source_node.getparent()
+        assert source_parent is not None, f"Target {source_node.get_id()} of {self.node.get_id()} should have a parent"
         cloned_node = clone_with_fixup(parent, source_node)
 
         if recursive:
@@ -201,7 +204,7 @@ class Clone(EmbroideryElement):
         if cloned_node.tag == SVG_SYMBOL_TAG:
             source_transform: Transform = parent.composed_transform()
         else:
-            source_transform: Transform = source_parent.composed_transform()
+            source_transform = source_parent.composed_transform()
         clone_transform: Transform = self.node.composed_transform()
         angle_transform = clone_transform @ -source_transform
         self.apply_angles(cloned_node, angle_transform)
@@ -242,7 +245,7 @@ class Clone(EmbroideryElement):
                 # We have to negate the angle because SVG/Inkscape's definition of rotation is clockwise, while Inkstitch uses counter-clockwise
                 fill_vector = (angle_transform @ Transform(f"rotate(${-element_angle})")).apply_to_point((1, 0))
                 # Same reason for negation here.
-                element_angle = -degrees(fill_vector.angle)
+                element_angle = -degrees(fill_vector.angle or 0)  # Fallback to 0 if an insane transform is used.
             else:  # If clone_fill_angle is specified, override the angle instead.
                 element_angle = self.clone_fill_angle
 
@@ -252,26 +255,28 @@ class Clone(EmbroideryElement):
             node.set(INKSTITCH_ATTRIBS['angle'], round(element_angle, 6))
 
     @property
-    def shape(self):
+    def shape(self) -> Geometry:
         path = self.node.get_path()
         transform = Transform(self.node.composed_transform())
         path = path.transform(transform)
         path = path.to_superpath()
         return MultiLineString(path[0])
 
-    def center(self, source_node):
+    def center(self, source_node: BaseElement) -> Vector2d:
         translate = Transform(f"translate({float(self.node.get('x', '0'))}, {float(self.node.get('y', '0'))})")
-        transform = get_node_transform(self.node.getparent()) @ translate
+        parent = self.node.getparent()
+        assert parent is not None, "This should be part of a tree and therefore have a parent"
+        transform = get_node_transform(parent) @ translate
         center = self.node.bounding_box(transform).center
         return center
 
-    def validation_warnings(self):
+    def validation_warnings(self) -> Generator[CloneWarning, Any, None]:
         source_node = self.node.href
         point = self.center(source_node)
         yield CloneWarning(point)
 
 
-def is_clone(node):
+def is_clone(node: BaseElement) -> bool:
     if node.tag == SVG_USE_TAG and node.href is not None and not is_command_symbol(node):
         return True
     return False
@@ -299,7 +304,7 @@ def clone_with_fixup(parent: BaseElement, node: BaseElement) -> BaseElement:
 
     ret = clone_children(parent, node)
 
-    def fixup_id_attr(node: BaseElement, attr: str):
+    def fixup_id_attr(node: BaseElement, attr: str) -> None:
         # Replace the id value for this attrib with the corresponding one in the clone subtree, if applicable.
         val = node.get(attr)
         if val is not None:
diff --git a/lib/elements/element.py b/lib/elements/element.py
index ea2d5d6b..6f2c52e9 100644
--- a/lib/elements/element.py
+++ b/lib/elements/element.py
@@ -2,6 +2,7 @@
 #
 # Copyright (c) 2010 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
+from __future__ import annotations
 import json
 import sys
 from contextlib import contextmanager
@@ -79,8 +80,9 @@ class EmbroideryElement(object):
             prop = getattr(cls, attr)
             if isinstance(prop, property):
                 # The 'param' attribute is set by the 'param' decorator defined above.
-                if hasattr(prop.fget, 'param'):
-                    params.append(prop.fget.param)
+                fget = prop.fget
+                if fget is not None and hasattr(fget, 'param'):
+                    params.append(fget.param)
         return params
 
     @cache
@@ -215,18 +217,18 @@ class EmbroideryElement(object):
 
         # First, figure out the translation component of the transform.  Using a zero
         # vector completely cancels out the rotation, scale, and skew components.
-        zero = [0, 0]
+        zero = (0, 0)
         zero = inkex.Transform.apply_to_point(node_transform, zero)
         translate = Point(*zero)
 
         # Next, see how the transform affects unit vectors in the X and Y axes.  We
         # need to subtract off the translation or it will affect the magnitude of
         # the resulting vector, which we don't want.
-        unit_x = [1, 0]
+        unit_x = (1, 0)
         unit_x = inkex.Transform.apply_to_point(node_transform, unit_x)
         sx = (Point(*unit_x) - translate).length()
 
-        unit_y = [0, 1]
+        unit_y = (0, 1)
         unit_y = inkex.Transform.apply_to_point(node_transform, unit_y)
         sy = (Point(*unit_y) - translate).length()
 
@@ -455,7 +457,7 @@ class EmbroideryElement(object):
         raise NotImplementedError("INTERNAL ERROR: %s must implement shape()", self.__class__)
 
     @property
-    def first_stitch(self):
+    def first_stitch(self) -> Optional[ShapelyPoint]:
         # first stitch is an approximation to where the first stitch may possibly be
         # if not defined through commands or repositioned by the previous element
         raise NotImplementedError("INTERNAL ERROR: %s must implement first_stitch()", self.__class__)
@@ -521,7 +523,7 @@ class EmbroideryElement(object):
 
         return lock_start, lock_end
 
-    def to_stitch_groups(self, last_stitch_group: Optional[StitchGroup], next_element: Optional[ShapelyPoint] = None) -> List[StitchGroup]:
+    def to_stitch_groups(self, last_stitch_group: Optional[StitchGroup], next_element: Optional[EmbroideryElement] = None) -> List[StitchGroup]:
         raise NotImplementedError("%s must implement to_stitch_groups()" % self.__class__.__name__)
 
     @debug.time
diff --git a/lib/elements/fill_stitch.py b/lib/elements/fill_stitch.py
index f8db39d5..ee77cd60 100644
--- a/lib/elements/fill_stitch.py
+++ b/lib/elements/fill_stitch.py
@@ -808,13 +808,17 @@ class FillStitch(EmbroideryElement):
     def validation_errors(self):
         if not self.shape.is_valid:
             why = explain_validity(self.shape)
-            message, x, y = re.match(r"(?P<message>.+)\[(?P<x>.+)\s(?P<y>.+)\]", why).groups()
+            match = re.match(r"(?P<message>.+)\[(?P<x>.+)\s(?P<y>.+)\]", why)
+            assert match is not None, f"Could not parse validity message '{why}'"
+            message, x, y = match.groups()
             yield InvalidShapeError((x, y))
 
     def validation_warnings(self):  # noqa: C901
         if not self.original_shape.is_valid:
             why = explain_validity(self.original_shape)
-            message, x, y = re.match(r"(?P<message>.+)\[(?P<x>.+)\s(?P<y>.+)\]", why).groups()
+            match = re.match(r"(?P<message>.+)\[(?P<x>.+)\s(?P<y>.+)\]", why)
+            assert match is not None, f"Could not parse validity message '{why}'"
+            message, x, y = match.groups()
             if "Hole lies outside shell" in message:
                 yield UnconnectedWarning((x, y))
             else:
diff --git a/lib/elements/image.py b/lib/elements/image.py
index 695515dc..ad012975 100644
--- a/lib/elements/image.py
+++ b/lib/elements/image.py
@@ -23,14 +23,16 @@ class ImageObject(EmbroideryElement):
     name = "Image"
 
     def center(self):
-        transform = get_node_transform(self.node.getparent())
+        parent = self.node.getparent()
+        assert parent is not None, "This should be part of a tree and therefore have a parent"
+        transform = get_node_transform(parent)
         center = self.node.bounding_box(transform).center
         return center
 
     def validation_warnings(self):
         yield ImageTypeWarning(self.center())
 
-    def to_stitch_groups(self, last_stitch_group):
+    def to_stitch_groups(self, last_stitch_group, next_element):
         return []
 
     def first_stitch(self):
diff --git a/lib/elements/text.py b/lib/elements/text.py
index dd886dbc..34ce14e2 100644
--- a/lib/elements/text.py
+++ b/lib/elements/text.py
@@ -21,7 +21,9 @@ class TextTypeWarning(ObjectTypeWarning):
 class TextObject(EmbroideryElement):
 
     def pointer(self):
-        transform = get_node_transform(self.node.getparent())
+        parent = self.node.getparent()
+        assert parent is not None, "This should be part of a tree and therefore have a parent"
+        transform = get_node_transform(parent)
         point = self.node.bounding_box(transform).center
 
         return point
diff --git a/lib/elements/utils.py b/lib/elements/utils.py
index dfe1eb3a..cf770af4 100644
--- a/lib/elements/utils.py
+++ b/lib/elements/utils.py
@@ -3,7 +3,7 @@
 # Copyright (c) 2010 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
-from typing import List, Optional
+from typing import List, Optional, Iterable
 
 from inkex import BaseElement
 from lxml.etree import Comment
@@ -41,7 +41,7 @@ def node_to_elements(node, clone_to_element=False) -> List[EmbroideryElement]:
         return [MarkerObject(node)]
 
     elif node.tag in EMBROIDERABLE_TAGS or is_clone(node):
-        elements = []
+        elements: List[EmbroideryElement] = []
 
         from ..sew_stack import SewStack
         sew_stack = SewStack(node)
@@ -73,7 +73,7 @@ def node_to_elements(node, clone_to_element=False) -> List[EmbroideryElement]:
         return []
 
 
-def nodes_to_elements(nodes):
+def nodes_to_elements(nodes: Iterable[BaseElement]) -> List[EmbroideryElement]:
     elements = []
     for node in nodes:
         elements.extend(node_to_elements(node))
@@ -89,7 +89,8 @@ def iterate_nodes(node: BaseElement,  # noqa: C901
     def walk(node: BaseElement, selected: bool) -> List[BaseElement]:
         nodes = []
 
-        if node.tag == Comment:
+        # lxml-stubs types are wrong, node.tag can be Comment.
+        if node.tag is Comment:  # type:ignore[comparison-overlap]
             return []
 
         element = EmbroideryElement(node)
diff --git a/lib/elements/validation.py b/lib/elements/validation.py
index 9ac8e745..8edcc7c5 100644
--- a/lib/elements/validation.py
+++ b/lib/elements/validation.py
@@ -3,6 +3,7 @@
 # Copyright (c) 2010 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
+from typing import Optional, List
 from shapely.geometry import Point as ShapelyPoint
 
 from ..utils import Point as InkstitchPoint
@@ -21,9 +22,9 @@ class ValidationMessage(object):
     '''
 
     # Subclasses will fill these in.
-    name = None
-    description = None
-    steps_to_solve = []
+    name: Optional[str] = None
+    description: Optional[str] = None
+    steps_to_solve: List[str] = []
 
     def __init__(self, position=None, label=""):
         if isinstance(position, ShapelyPoint):
diff --git a/lib/extensions/__init__.py b/lib/extensions/__init__.py
index 9b25ff91..289cac31 100644
--- a/lib/extensions/__init__.py
+++ b/lib/extensions/__init__.py
@@ -77,76 +77,78 @@ from .update_svg import UpdateSvg
 from .zigzag_line_to_satin import ZigzagLineToSatin
 from .zip import Zip
 
-__all__ = extensions = [About,
-                        ApplyPalette,
-                        ApplyThreadlist,
-                        AutoRun,
-                        AutoSatin,
-                        BreakApart,
-                        Cleanup,
-                        CommandsScaleSymbols,
-                        ConvertToSatin,
-                        ConvertToStroke,
-                        CutSatin,
-                        CutworkSegmentation,
-                        DensityMap,
-                        DisplayStackingOrder,
-                        DuplicateParams,
-                        ElementInfo,
-                        FillToSatin,
-                        FillToStroke,
-                        Flip,
-                        GeneratePalette,
-                        GlobalCommands,
-                        GradientBlocks,
-                        Input,
-                        Install,
-                        InstallCustomPalette,
-                        JumpToStroke,
-                        JumpToTrim,
-                        KnockdownFill,
-                        LayerCommands,
-                        Lettering,
-                        LetteringAlongPath,
-                        LetteringCustomFontDir,
-                        LetteringEditJson,
-                        LetteringFontSample,
-                        LetteringForceLockStitches,
-                        LetteringGenerateJson,
-                        LetteringRemoveKerning,
-                        LetteringSetColorSortIndex,
-                        LetteringSvgFontToLayers,
-                        LettersToFont,
-                        ObjectCommands,
-                        ObjectCommandsToggleVisibility,
-                        Outline,
-                        Output,
-                        PaletteSplitText,
-                        PaletteToText,
-                        Params,
-                        PngRealistic,
-                        PngSimple,
-                        Preferences,
-                        Print,
-                        Redwork,
-                        RemoveDuplicatedPoints,
-                        RemoveEmbroiderySettings,
-                        Reorder,
-                        SatinMulticolor,
-                        SelectElements,
-                        SelectionToAnchorLine,
-                        SelectionToGuideLine,
-                        SelectionToPattern,
-                        SewStackEditor,
-                        Simulator,
-                        StitchPlanPreview,
-                        StitchPlanPreviewUndo,
-                        StrokeToLpeSatin,
-                        Tartan,
-                        TestSwatches,
-                        ThreadList,
-                        Troubleshoot,
-                        UnlinkClone,
-                        UpdateSvg,
-                        ZigzagLineToSatin,
-                        Zip]
+extensions = [
+    About,
+    ApplyPalette,
+    ApplyThreadlist,
+    AutoRun,
+    AutoSatin,
+    BreakApart,
+    Cleanup,
+    CommandsScaleSymbols,
+    ConvertToSatin,
+    ConvertToStroke,
+    CutSatin,
+    CutworkSegmentation,
+    DensityMap,
+    DisplayStackingOrder,
+    DuplicateParams,
+    ElementInfo,
+    FillToSatin,
+    FillToStroke,
+    Flip,
+    GeneratePalette,
+    GlobalCommands,
+    GradientBlocks,
+    Input,
+    Install,
+    InstallCustomPalette,
+    JumpToStroke,
+    JumpToTrim,
+    KnockdownFill,
+    LayerCommands,
+    Lettering,
+    LetteringAlongPath,
+    LetteringCustomFontDir,
+    LetteringEditJson,
+    LetteringFontSample,
+    LetteringForceLockStitches,
+    LetteringGenerateJson,
+    LetteringRemoveKerning,
+    LetteringSetColorSortIndex,
+    LetteringSvgFontToLayers,
+    LettersToFont,
+    ObjectCommands,
+    ObjectCommandsToggleVisibility,
+    Outline,
+    Output,
+    PaletteSplitText,
+    PaletteToText,
+    Params,
+    PngRealistic,
+    PngSimple,
+    Preferences,
+    Print,
+    Redwork,
+    RemoveDuplicatedPoints,
+    RemoveEmbroiderySettings,
+    Reorder,
+    SatinMulticolor,
+    SelectElements,
+    SelectionToAnchorLine,
+    SelectionToGuideLine,
+    SelectionToPattern,
+    SewStackEditor,
+    Simulator,
+    StitchPlanPreview,
+    StitchPlanPreviewUndo,
+    StrokeToLpeSatin,
+    Tartan,
+    TestSwatches,
+    ThreadList,
+    Troubleshoot,
+    UnlinkClone,
+    UpdateSvg,
+    ZigzagLineToSatin,
+    Zip
+]
diff --git a/lib/extensions/cleanup.py b/lib/extensions/cleanup.py
index d5816b5f..366d8547 100644
--- a/lib/extensions/cleanup.py
+++ b/lib/extensions/cleanup.py
@@ -60,12 +60,12 @@ class Cleanup(InkstitchExtension):
     def _dry_run(self):
         errormsg(_("%s elements to remove:" % len(self.elements_to_remove)))
         for element in self.elements_to_remove:
-            errormsg(f" - { element.label }: {element.get_id()}")
+            errormsg(f" - {element.label}: {element.get_id()}")
 
         errormsg("\n")
         errormsg(_("%s groups/layers to remove:" % len(self.groups_to_remove)))
         for group in self.groups_to_remove:
-            errormsg(f" - { group.label }: {group.get_id()}")
+            errormsg(f" - {group.label}: {group.get_id()}")
 
     def _remove(self):
         num_elements_removed = len(self.elements_to_remove)
diff --git a/lib/extensions/cutwork_segmentation.py b/lib/extensions/cutwork_segmentation.py
index bea14472..c041e359 100644
--- a/lib/extensions/cutwork_segmentation.py
+++ b/lib/extensions/cutwork_segmentation.py
@@ -136,7 +136,7 @@ class CutworkSegmentation(InkstitchExtension):
 
         d = "M "
         for point in point_list:
-            d += f"{ point.x }, { point.y } "
+            d += f"{point.x}, {point.y} "
 
         stroke_element = inkex.PathElement(attrib={
             "style": color,
@@ -188,4 +188,4 @@ class CutworkSegmentation(InkstitchExtension):
 
     def path_style(self, element, color):
         # set stroke color and make it a running stitch - they don't want to cut zigzags
-        return inkex.Style(element.node.get('style', '')) + inkex.Style(f'stroke-width:1;stroke:{ color };')
+        return inkex.Style(element.node.get('style', '')) + inkex.Style(f'stroke-width:1;stroke:{color};')
diff --git a/lib/extensions/display_stacking_order.py b/lib/extensions/display_stacking_order.py
index ba5fda98..f9f83ca4 100644
--- a/lib/extensions/display_stacking_order.py
+++ b/lib/extensions/display_stacking_order.py
@@ -38,7 +38,7 @@ class DisplayStackingOrder(InkstitchExtension):
             'x': str(position[0]),
             'y': str(position[1])
         })
-        text.style = inkex.Style(f"text-anchor: middle;text-align: center;dominant-baseline: middle;font-size: { self.options.font_size }")
+        text.style = inkex.Style(f"text-anchor: middle;text-align: center;dominant-baseline: middle;font-size: {self.options.font_size}")
         tspan = inkex.Tspan()
         tspan.text = str(num)
         text.add(tspan)
diff --git a/lib/extensions/element_info.py b/lib/extensions/element_info.py
index b84232b7..06acbb16 100644
--- a/lib/extensions/element_info.py
+++ b/lib/extensions/element_info.py
@@ -48,7 +48,7 @@ class ElementInfo(InkstitchExtension):
         )
 
         self.list_items.append(ListItem(
-            name=f"{ element.node.label } ({ element.node.get_id() })",
+            name=f"{element.node.label} ({element.node.get_id()})",
             value=stitch_groups[0].color,
             headline=True
         ))
@@ -116,7 +116,7 @@ class ElementInfo(InkstitchExtension):
 
         stitches_per_group = ""
         if len(stitch_groups) > 1:
-            stitches_per_group = f" ({', '.join([str(len(group.stitches)) for group in stitch_groups]) })"
+            stitches_per_group = f" ({', '.join([str(len(group.stitches)) for group in stitch_groups])})"
 
         self.list_items.append(ListItem(
             name=_("Stitches"),
@@ -200,7 +200,7 @@ class ElementInfo(InkstitchExtension):
 
 
 class ListItem:
-    def __init__(self, name="", value="", headline=False, warning=False):
+    def __init__(self, name="", value="", headline=False, warning=False) -> None:
         self.name: str = name
         self.value: str = value
         self.headline: bool = headline
diff --git a/lib/extensions/fill_to_stroke.py b/lib/extensions/fill_to_stroke.py
index 9101eca2..085b3c95 100644
--- a/lib/extensions/fill_to_stroke.py
+++ b/lib/extensions/fill_to_stroke.py
@@ -67,7 +67,7 @@ class FillToStroke(InkstitchExtension):
         element_label = element.node.label
         group_name = element_label or element_id
 
-        centerline_group = Group.new(f'{ group_name } { _("center line") }', id=self.uniqueId("centerline_group_"))
+        centerline_group = Group.new(f'{group_name} { _("center line") }', id=self.uniqueId("centerline_group_"))
         parent = element.node.getparent()
         index = parent.index(element.node) + 1
         parent.insert(index, centerline_group)
@@ -75,7 +75,7 @@ class FillToStroke(InkstitchExtension):
         transform = Transform(get_correction_transform(parent, child=True))
         stroke_width = convert_unit(self.options.line_width_mm, 'px', 'mm')
         color = element.node.style('fill')
-        style = f"fill:none;stroke:{ color };stroke-width:{ stroke_width }"
+        style = f"fill:none;stroke:{color};stroke-width:{stroke_width}"
 
         multipolygon = element.shape
         multipolygon = self._apply_cut_lines(cut_lines, multipolygon)
diff --git a/lib/extensions/generate_palette.py b/lib/extensions/generate_palette.py
index b87bc179..6cc839fb 100644
--- a/lib/extensions/generate_palette.py
+++ b/lib/extensions/generate_palette.py
@@ -84,4 +84,4 @@ class GeneratePalette(InkstitchExtension):
 
 if __name__ == '__main__':
     e = GeneratePalette()
-    e.affect()
+    e.run()
diff --git a/lib/extensions/gradient_blocks.py b/lib/extensions/gradient_blocks.py
index 8e341cc8..9ae24736 100644
--- a/lib/extensions/gradient_blocks.py
+++ b/lib/extensions/gradient_blocks.py
@@ -173,4 +173,4 @@ def gradient_shapes_and_attributes(element, shape, unit_multiplier):
 
 if __name__ == '__main__':
     e = GradientBlocks()
-    e.effect()
+    e.run()
diff --git a/lib/extensions/palette_to_text.py b/lib/extensions/palette_to_text.py
index 729c92fc..8c3db035 100644
--- a/lib/extensions/palette_to_text.py
+++ b/lib/extensions/palette_to_text.py
@@ -55,4 +55,4 @@ class PaletteToText(InkstitchExtension):
 
 if __name__ == '__main__':
     e = PaletteToText()
-    e.affect()
+    e.run()
diff --git a/lib/extensions/reorder.py b/lib/extensions/reorder.py
index 956c0615..2c10559d 100644
--- a/lib/extensions/reorder.py
+++ b/lib/extensions/reorder.py
@@ -34,4 +34,4 @@ class Reorder(InkstitchExtension):
 
 if __name__ == '__main__':
     e = Reorder()
-    e.affect()
+    e.run()
diff --git a/lib/extensions/sew_stack_editor.py b/lib/extensions/sew_stack_editor.py
index a7cc9e38..3b703225 100755
--- a/lib/extensions/sew_stack_editor.py
+++ b/lib/extensions/sew_stack_editor.py
@@ -6,8 +6,8 @@ import sys
 
 import wx
 from wx.lib.agw import ultimatelistctrl as ulc
-from wx.lib.checkbox import GenCheckBox
-from wx.lib.splitter import MultiSplitterWindow
+from wx.lib.checkbox import GenCheckBox  # type:ignore[import-untyped]
+from wx.lib.splitter import MultiSplitterWindow  # type:ignore[import-untyped]
 
 from .base import InkstitchExtension
 from ..debug.debug import debug
diff --git a/lib/extensions/stroke_to_lpe_satin.py b/lib/extensions/stroke_to_lpe_satin.py
index 7d4ffb3e..3c0ed017 100644
--- a/lib/extensions/stroke_to_lpe_satin.py
+++ b/lib/extensions/stroke_to_lpe_satin.py
@@ -165,7 +165,7 @@ class StrokeToLpeSatin(InkstitchExtension):
 
 
 class SatinPattern:
-    def __init__(self, path=None, node_types=None, flip=True, rung_node=1):
+    def __init__(self, path=None, node_types=None, flip=True, rung_node=1) -> None:
         self.path: str = path
         self.node_types: str = node_types
         self.flip: bool = flip
diff --git a/lib/extensions/unlink_clone.py b/lib/extensions/unlink_clone.py
index bebfbdb8..b4af7961 100644
--- a/lib/extensions/unlink_clone.py
+++ b/lib/extensions/unlink_clone.py
@@ -3,7 +3,7 @@
 # Copyright (c) 2010 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
-from typing import List, Tuple
+from typing import List, Tuple, cast
 
 from inkex import BaseElement, Boolean, Group, errormsg
 
@@ -19,7 +19,7 @@ class UnlinkClone(InkstitchExtension):
         self.arg_parser.add_argument("--notebook")
         self.arg_parser.add_argument("-r", "--recursive", dest="recursive", type=Boolean, default=True)
 
-    def effect(self):
+    def effect(self) -> None:
         recursive: bool = self.options.recursive
 
         if not self.get_elements():
@@ -39,15 +39,16 @@ class UnlinkClone(InkstitchExtension):
                     group = Group()
                     for child in resolved[0]:
                         group.append(child)
-                    resolved[0].getparent().replace(resolved[0], group)
+                    parent = cast(BaseElement, resolved[0].getparent())  # Safe assumption that this has a parent.
+                    parent.replace(resolved[0], group)
                 clones_resolved.append((element.node, resolved[0]))
 
-        for (clone, resolved) in clones_resolved:
+        for (clone, resolved_clone) in clones_resolved:
             clone.delete()
-            orig_id = resolved.get_id()
+            orig_id = resolved_clone.get_id()
             new_id = clone.get_id()
             # Fix up command backlinks - note this has to happen before we rename so they can actually be found.
-            for command in EmbroideryElement(resolved).commands:
+            for command in EmbroideryElement(resolved_clone).commands:
                 backlink_attrib = CONNECTION_START if command.connector.get(CONNECTION_START) == ("#"+orig_id) else CONNECTION_END
                 command.connector.set(backlink_attrib, "#"+new_id)
-            resolved.set_id(new_id)
+            resolved_clone.set_id(new_id)
diff --git a/lib/gui/edit_json/editable_list.py b/lib/gui/edit_json/editable_list.py
index fc033597..8f62f554 100644
--- a/lib/gui/edit_json/editable_list.py
+++ b/lib/gui/edit_json/editable_list.py
@@ -1,5 +1,5 @@
 import wx
-from wx.lib.mixins.listctrl import TextEditMixin
+from wx.lib.mixins.listctrl import TextEditMixin  # type: ignore[import-untyped]
 
 
 class EditableListCtrl(wx.ListCtrl, TextEditMixin):
diff --git a/lib/i18n.py b/lib/i18n.py
index 2a901a0e..b2a2b002 100644
--- a/lib/i18n.py
+++ b/lib/i18n.py
@@ -5,30 +5,27 @@
 
 import gettext
 import os
+from typing import Callable, Tuple
 
 from .utils import cache, get_resource_dir
 
-_ = translation = None
-locale_dir = None
-
 # Use N_ to mark a string for translation but _not_ immediately translate it.
 # reference: https://docs.python.org/3/library/gettext.html#deferred-translations
 # Makefile configures pybabel to treat N_() the same as _()
 
 
-def N_(message): return message
+def N_(message: str) -> str:
+    return message
 
 
-def _set_locale_dir():
-    global locale_dir
+def localize(languages=None) -> Tuple[Callable[[str], str], gettext.NullTranslations]:
     locale_dir = get_resource_dir('locales')
 
-
-def localize(languages=None):
     global translation, _
 
     translation = gettext.translation("inkstitch", locale_dir, fallback=True)
     _ = translation.gettext
+    return (_, translation)
 
 
 @cache
@@ -53,5 +50,4 @@ def get_languages():
     return languages
 
 
-_set_locale_dir()
-localize()
+_, translation = localize()
diff --git a/lib/lettering/categories.py b/lib/lettering/categories.py
index 9a63063a..e7e81b3f 100644
--- a/lib/lettering/categories.py
+++ b/lib/lettering/categories.py
@@ -7,9 +7,9 @@ from ..i18n import _
 
 
 class FontCategory:
-    def __init__(self, cat_id=None, name=None):
-        self.id: str = cat_id
-        self.name: str = name
+    def __init__(self, cat_id: str, name: str) -> None:
+        self.id = cat_id
+        self.name = name
 
     def __repr__(self):
         return "FontCategory(%s, %s)" % (self.id, self.name)
@@ -35,5 +35,4 @@ FONT_CATEGORIES = [
     FontCategory('hebrew', _("Script: hebrew")),
     FontCategory('japanese', _("Script: japanese")),
     FontCategory('latin', _("Script: latin"))
-
 ]
diff --git a/lib/lettering/font_info.py b/lib/lettering/font_info.py
index 74cc0967..8bf35900 100644
--- a/lib/lettering/font_info.py
+++ b/lib/lettering/font_info.py
@@ -5,7 +5,7 @@
 
 from collections import defaultdict
 
-from fontTools.agl import toUnicode
+from fontTools.agl import toUnicode  # type:ignore[import-untyped]
 from inkex import NSS
 from lxml import etree
 
diff --git a/lib/output.py b/lib/output.py
index 4559ca2b..a16b4018 100644
--- a/lib/output.py
+++ b/lib/output.py
@@ -32,11 +32,6 @@ def get_command(stitch):
         return pyembroidery.NEEDLE_AT
 
 
-def _string_to_floats(string):
-    floats = string.split(',')
-    return [float(num) for num in floats]
-
-
 def get_origin(svg, bounding_box):
     (minx, miny, maxx, maxy) = bounding_box
     origin_command = global_command(svg, "origin")
diff --git a/lib/sew_stack/stitch_layers/stitch_layer.py b/lib/sew_stack/stitch_layers/stitch_layer.py
index 4b34373a..615a36e8 100644
--- a/lib/sew_stack/stitch_layers/stitch_layer.py
+++ b/lib/sew_stack/stitch_layers/stitch_layer.py
@@ -1,10 +1,12 @@
+from typing import Type
 from ...utils import coordinate_list_to_point_list
 from ...utils.dotdict import DotDict
+from .stitch_layer_editor import StitchLayerEditor
 
 
 class StitchLayer:
     # must be overridden in child classes and set to a subclass of StitchLayerEditor
-    editor_class = None
+    editor_class: Type[StitchLayerEditor] = None  # type:ignore[assignment]
 
     # not to be overridden in child classes
     _defaults = None
diff --git a/lib/stitch_plan/lock_stitch.py b/lib/stitch_plan/lock_stitch.py
index 899aa382..98219154 100755
--- a/lib/stitch_plan/lock_stitch.py
+++ b/lib/stitch_plan/lock_stitch.py
@@ -1,5 +1,6 @@
 import re
 from math import degrees
+from typing import List, Optional
 
 from inkex import DirectedLineSegment, Path
 from shapely.geometry import LineString
@@ -12,16 +13,16 @@ from .stitch import Stitch
 
 
 class LockStitchDefinition:
-    def __init__(self, lock_id=None, name=None, path=None, preview_image=None):
+    def __init__(self, lock_id=None, name=None, path=None, preview_image=None) -> None:
         self.id: str = lock_id
         self.name: str = name
         self._path: str = path
-        self.preview_image: str = None
+        self.preview_image: Optional[str] = None
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "LockStitchDefinition(%s, %s, %s, %s)" % (self.id, self.name, self._path, self.preview_image)
 
-    def stitches(self, stitches, pos, scale):
+    def stitches(self, stitches, pos, scale) -> List[Stitch]:
         raise NotImplementedError(f"{self.__class__.__name__} must implement stitches()")
 
 
diff --git a/lib/stitch_plan/stitch.py b/lib/stitch_plan/stitch.py
index ffa944ae..bce7c05a 100644
--- a/lib/stitch_plan/stitch.py
+++ b/lib/stitch_plan/stitch.py
@@ -3,6 +3,8 @@
 # Copyright (c) 2010 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
+from __future__ import annotations  # Needed for using the Stitch type as a constructor arg
+from typing import Dict, Type, Union, Optional, Set, Any, Iterable, overload
 from shapely import geometry as shgeo
 
 from ..utils.geometry import Point
@@ -10,17 +12,80 @@ from ..utils.geometry import Point
 
 class Stitch(Point):
     """A stitch is a Point with extra information telling how to sew it."""
+    x: float
+    y: float
+    color: Any  # Todo: What is this
+    jump: bool
+    stop: bool
+    trim: bool
+    color_change: bool
+    min_stitch_length: Optional[float]
+    tags: Set[str]
+
+    @overload
+    def __init__(
+        self,
+        x: Stitch,
+        color: Optional[Any] = None,
+        jump=False,
+        stop=False,
+        trim=False,
+        color_change=False,
+        min_stitch_length: Optional[float] = None,
+        tags: Optional[Iterable[str]] = None
+    ): ...
 
+    @overload
     def __init__(
         self,
-        x, y=None,
-        color=None,
+        x: Point,
+        color: Optional[Any] = None,
         jump=False,
         stop=False,
         trim=False,
         color_change=False,
-        min_stitch_length=None,
-        tags=None
+        min_stitch_length: Optional[float] = None,
+        tags: Optional[Iterable[str]] = None
+    ): ...
+
+    @overload
+    def __init__(
+        self,
+        x: shgeo.Point,
+        color: Optional[Any] = None,
+        jump=False,
+        stop=False,
+        trim=False,
+        color_change=False,
+        min_stitch_length: Optional[float] = None,
+        tags: Optional[Iterable[str]] = None
+    ): ...
+
+    @overload
+    def __init__(
+        self,
+        x: float,
+        y: float,
+        color: Optional[Any] = None,
+        jump: bool = False,
+        stop: bool = False,
+        trim: bool = False,
+        color_change: bool = False,
+        min_stitch_length: Optional[float] = None,
+        tags: Optional[Iterable[str]] = None
+    ): ...
+
+    def __init__(
+        self,
+        x: Union[Stitch, float, Point],
+        y: Optional[float] = None,
+        color: Optional[Any] = None,
+        jump: bool = False,
+        stop: bool = False,
+        trim: bool = False,
+        color_change: bool = False,
+        min_stitch_length: Optional[float] = None,
+        tags: Optional[Iterable[str]] = None
     ):
         # DANGER: if you add new attributes, you MUST also set their default
         # values in __new__() below.  Otherwise, cached stitch plans can be
@@ -32,14 +97,15 @@ class Stitch(Point):
             # Allow creating a Stitch from another Stitch.  Attributes passed as
             # arguments will override any existing attributes.
             base_stitch = x
-            self.x: float = base_stitch.x
-            self.y: float = base_stitch.y
+            self.x = base_stitch.x
+            self.y = base_stitch.y
         elif isinstance(x, (Point, shgeo.Point)):
             # Allow creating a Stitch from a Point
             point = x
-            self.x: float = point.x
-            self.y: float = point.y
+            self.x = point.x
+            self.y = point.y
         else:
+            assert y is not None, "Bad stitch constructor use: No y component?"
             Point.__init__(self, x, y)
 
         self._set('color', color, base_stitch)
@@ -54,7 +120,7 @@ class Stitch(Point):
         if base_stitch is not None:
             self.add_tags(base_stitch.tags)
 
-    def __new__(cls, *args, **kwargs):
+    def __new__(cls: Type[Stitch], *args, **kwargs) -> Stitch:
         instance = super().__new__(cls)
 
         # Set default values for any new attributes here (see note in __init__() above)
@@ -74,7 +140,7 @@ class Stitch(Point):
             "COLOR CHANGE" if self.color_change else " "
         )
 
-    def _set(self, attribute, value, base_stitch):
+    def _set(self, attribute: str, value: Optional[Any], base_stitch: Optional[Stitch]) -> None:
         # Set an attribute.  If the caller passed a Stitch object, use its value, unless
         # they overrode it with arguments.
         if base_stitch is not None:
@@ -86,11 +152,11 @@ class Stitch(Point):
     def is_terminator(self) -> bool:
         return self.trim or self.stop or self.color_change
 
-    def add_tags(self, tags):
+    def add_tags(self, tags: Iterable[str]) -> None:
         for tag in tags:
             self.add_tag(tag)
 
-    def add_tag(self, tag):
+    def add_tag(self, tag: str) -> None:
         """Store arbitrary information about a stitch.
 
         Tags can be used to store any information about a stitch.  This can be
@@ -105,10 +171,10 @@ class Stitch(Point):
         """
         self.tags.add(tag)
 
-    def has_tag(self, tag):
+    def has_tag(self, tag: str) -> bool:
         return tag in self.tags
 
-    def copy(self):
+    def copy(self) -> Stitch:
         return Stitch(
             self.x,
             self.y,
@@ -121,18 +187,18 @@ class Stitch(Point):
             self.tags
         )
 
-    def offset(self, offset: Point):
+    def offset(self, offset: Point) -> Stitch:
         out = self.copy()
         out.x += offset.x
         out.y += offset.y
         return out
 
-    def __json__(self):
+    def __json__(self) -> Dict[str, Any]:
         attributes = dict(vars(self))
         attributes['tags'] = list(attributes['tags'])
         return attributes
 
-    def __getstate__(self):
+    def __getstate__(self) -> Dict[str, Any]:
         # This is used by pickle.  We want to sort the tag list so that the
         # pickled representation is stable, since it's used to generate cache
         # keys.
diff --git a/lib/stitches/guided_fill.py b/lib/stitches/guided_fill.py
index 6ad80da0..5d9a6018 100644
--- a/lib/stitches/guided_fill.py
+++ b/lib/stitches/guided_fill.py
@@ -172,7 +172,7 @@ def apply_stitches(line, max_stitch_length, num_staggers, row_spacing, row_num,
 
     if len(points) < 2:
         coords = line.coords
-        points = [coords[0], coords[-1]]
+        points = np.array([coords[0], coords[-1]])
 
     stitched_line = shgeo.LineString(points)
 
diff --git a/lib/stitches/running_stitch.py b/lib/stitches/running_stitch.py
index 6144a977..a773fa9a 100644
--- a/lib/stitches/running_stitch.py
+++ b/lib/stitches/running_stitch.py
@@ -33,7 +33,9 @@ def split_segment_even_n(a, b, segments: int, jitter_sigma: float = 0.0, random_
         splits = splits + jitters * (jitter_sigma / segments)
 
     # sort the splits in case a bad roll transposes any of them
-    return [line.interpolate(x, normalized=True) for x in sorted(splits)]
+    splits.sort()
+
+    return [line.interpolate(x, normalized=True) for x in splits]
 
 
 def split_segment_even_dist(a, b, max_length: float, jitter_sigma: float = 0.0, random_seed=None) -> typing.List[shgeo.Point]:
@@ -80,7 +82,7 @@ class AngleInterval():
     # partially based on https://fgiesen.wordpress.com/2015/09/24/intervals-in-modular-arithmetic/
 
     def __init__(self, a: float, b: float, all: bool = False):
-        self.all = all
+        self.isAll = all
         self.a = a
         self.b = b
 
@@ -111,7 +113,7 @@ class AngleInterval():
             return AngleInterval(angleB - 1e-6, angleA + 1e-6)
 
     def containsAngle(self, angle: float):
-        if self.all:
+        if self.isAll:
             return True
         return (angle - self.a) % tau <= (self.b - self.a) % tau
 
@@ -122,9 +124,9 @@ class AngleInterval():
         # assume that each interval contains less than half the circle (or all of it)
         if other is None:
             return None
-        elif self.all:
+        elif self.isAll:
             return other
-        elif other.all:
+        elif other.isAll:
             return self
         elif self.containsAngle(other.a):
             if other.containsAngle(self.b):
@@ -140,7 +142,7 @@ class AngleInterval():
             return None
 
     def cutSegment(self, origin: Point, a: Point, b: Point):
-        if self.all:
+        if self.isAll:
             return None
         segArc = AngleInterval.fromSegment(a - origin, b - origin)
         if segArc is None:
@@ -180,7 +182,8 @@ def cut_segment_with_circle(origin: Point, r: float, a: Point, b: Point) -> Poin
     return a + d*t
 
 
-def take_stitch(start: Point, points: typing.Sequence[Point], idx: int, stitch_length: float, tolerance: float):
+def take_stitch(start: Point, points: typing.Sequence[Point], idx: int, stitch_length: float, tolerance: float) -> \
+        typing.Tuple[typing.Optional[Point], typing.Optional[int]]:
     # Based on a single step of the Zhao-Saalfeld curve simplification algorithm.
     # https://cartogis.org/docs/proceedings/archive/auto-carto-13/pdf/linear-time-sleeve-fitting-polyline-simplification-algorithms.pdf
     # Adds early termination condition based on stitch length.
@@ -207,7 +210,7 @@ def take_stitch(start: Point, points: typing.Sequence[Point], idx: int, stitch_l
     return points[-1], None
 
 
-def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, tolerance: float):
+def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, tolerance: float) -> typing.List[Point]:
     # Will split a straight line into even-length stitches while still handling curves correctly.
     # Includes end point but not start point.
     if len(points) < 2:
@@ -216,9 +219,9 @@ def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, to
     for i in reversed(range(0, len(points) - 1)):
         distLeft[i] = distLeft[i + 1] + points[i].distance(points[i+1])
 
-    i = 1
+    i: typing.Optional[int] = 1
     last = points[0]
-    stitches = []
+    stitches: typing.List[Point] = []
     while i is not None and i < len(points):
         d = last.distance(points[i]) + distLeft[i]
         if d == 0:
@@ -233,7 +236,8 @@ def stitch_curve_evenly(points: typing.Sequence[Point], stitch_length: float, to
     return stitches
 
 
-def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float, tolerance: float, stitch_length_sigma: float, random_seed: str):
+def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float, tolerance: float, stitch_length_sigma: float, random_seed: str) ->\
+      typing.List[Point]:
     min_stitch_length = max(0, stitch_length * (1 - stitch_length_sigma))
     max_stitch_length = stitch_length * (1 + stitch_length_sigma)
     # Will split a straight line into stitches of random length within the range.
@@ -242,7 +246,7 @@ def stitch_curve_randomly(points: typing.Sequence[Point], stitch_length: float,
     if len(points) < 2:
         return []
 
-    i = 1
+    i: typing.Optional[int] = 1
     last = points[0]
     last_shortened = 0.0
     stitches = []
diff --git a/lib/stitches/tartan_fill.py b/lib/stitches/tartan_fill.py
index 1ddd8195..c25bb435 100644
--- a/lib/stitches/tartan_fill.py
+++ b/lib/stitches/tartan_fill.py
@@ -3,6 +3,9 @@
 # Copyright (c) 2023 Authors
 # Licensed under the GNU GPL version 3.0 or later.  See the file LICENSE for details.
 
+# This file needs some more love before it'll pass type checking.
+# mypy: ignore-errors=true
+
 from collections import defaultdict
 from itertools import chain
 from math import cos, radians, sin
diff --git a/lib/svg/path.py b/lib/svg/path.py
index 548a82f2..5e6e7007 100644
--- a/lib/svg/path.py
+++ b/lib/svg/path.py
@@ -9,7 +9,7 @@ from .tags import SVG_GROUP_TAG, SVG_LINK_TAG
 from .units import get_viewbox_transform
 
 
-def apply_transforms(path, node):
+def apply_transforms(path: inkex.Path, node: inkex.BaseElement) -> inkex.Path:
     transform = get_node_transform(node)
 
     # apply the combined transform to this node's path
@@ -18,20 +18,21 @@ def apply_transforms(path, node):
     return path
 
 
-def compose_parent_transforms(node, mat):
+def compose_parent_transforms(node: inkex.BaseElement, mat: inkex.Transform) -> inkex.Transform:
     # This is adapted from Inkscape's simpletransform.py's composeParents()
     # function.  That one can't handle nodes that are detached from a DOM.
 
     trans = node.get('transform')
     if trans:
         mat = inkex.transforms.Transform(trans) @ mat
-    if node.getparent() is not None:
-        if node.getparent().tag in [SVG_GROUP_TAG, SVG_LINK_TAG]:
-            mat = compose_parent_transforms(node.getparent(), mat)
+    parent = node.getparent()
+    if parent is not None:
+        if parent.tag in [SVG_GROUP_TAG, SVG_LINK_TAG]:
+            mat = compose_parent_transforms(parent, mat)
     return mat
 
 
-def get_node_transform(node: inkex.BaseElement):
+def get_node_transform(node: inkex.BaseElement) -> inkex.Transform:
     """
     if getattr(node, "composed_transform", None):
         return node.composed_transform()
@@ -52,7 +53,7 @@ def get_node_transform(node: inkex.BaseElement):
     return transform
 
 
-def get_correction_transform(node, child=False):
+def get_correction_transform(node: inkex.BaseElement, child=False) -> str:
     """Get a transform to apply to new siblings or children of this SVG node
 
     Arguments:
@@ -71,7 +72,11 @@ def get_correction_transform(node, child=False):
     else:
         # we can ignore the transform on the node itself since it won't apply
         # to the objects we add
-        transform = get_node_transform(node.getparent())
+        parent = node.getparent()
+        if parent is not None:
+            transform = get_node_transform(parent)
+        else:
+            transform = inkex.Transform()
 
     # now invert it, so that we can position our objects in absolute
     # coordinates
diff --git a/lib/tartan/fill_element.py b/lib/tartan/fill_element.py
index 34139e6c..6666181e 100644
--- a/lib/tartan/fill_element.py
+++ b/lib/tartan/fill_element.py
@@ -12,12 +12,13 @@ def prepare_tartan_fill_element(element: BaseElement) -> None:
     :param element: svg element with a fill color (path, rectangle, or circle)
     """
     parent_group = element.getparent()
-    if parent_group.get_id().startswith('inkstitch-tartan'):
+    if parent_group is not None and parent_group.get_id().startswith('inkstitch-tartan'):
         # apply tartan group transform to element
         transform = element.transform @ parent_group.transform
         element.set('transform', transform)
         # remove tartan group and place element in parent group
         outer_group = parent_group.getparent()
+        assert outer_group is not None, f"Tartan element {element.get_id()} should have a parent group"
         outer_group.insert(outer_group.index(parent_group), element)
         outer_group.remove(parent_group)
     # make sure the element is invisible
diff --git a/lib/tartan/palette.py b/lib/tartan/palette.py
index d945eb83..25bd2100 100644
--- a/lib/tartan/palette.py
+++ b/lib/tartan/palette.py
@@ -5,12 +5,14 @@
 # Additional credits to: https://github.com/clsn/pyTartan
 
 import re
-from typing import List
+from typing import TYPE_CHECKING, List, cast
 
 import wx
 from inkex import Color
 
 from .colors import string_to_color
+if TYPE_CHECKING:
+    from ..gui.tartan.stripe_panel import StripePanel
 
 
 class Palette:
@@ -59,7 +61,7 @@ class Palette:
             stripes = []
             for stripe_sizer in outer_sizer.Children:
                 stripe = {'render': 1, 'color': '#000000', 'width': '5'}
-                stripe_panel = stripe_sizer.GetWindow()
+                stripe_panel = cast('StripePanel', stripe_sizer.GetWindow())
                 stripe['render'] = stripe_panel.visibility.Get3StateValue()
                 stripe['color'] = stripe_panel.colorpicker.GetColour().GetAsString(wx.C2S_HTML_SYNTAX)
                 stripe['width'] = stripe_panel.stripe_width.GetValue()
diff --git a/lib/tartan/svg.py b/lib/tartan/svg.py
index 497d0199..62d737c9 100644
--- a/lib/tartan/svg.py
+++ b/lib/tartan/svg.py
@@ -7,7 +7,7 @@ import time
 from collections import defaultdict
 from copy import copy
 from itertools import chain
-from typing import List, Optional, Tuple
+from typing import List, Optional, Tuple, cast
 
 from inkex import BaseElement, Group, Path, PathElement
 from networkx import MultiGraph, is_empty
@@ -66,12 +66,12 @@ class TartanSvgGroup:
         :param outline: the outline to be filled with the tartan pattern
         """
         parent_group = outline.getparent()
-        if parent_group.get_id().startswith('inkstitch-tartan'):
+        if parent_group is not None and parent_group.get_id().startswith('inkstitch-tartan'):
             # remove everything but the tartan outline
             for child in parent_group.iterchildren():
                 if child != outline:
                     parent_group.remove(child)
-            group = parent_group
+            group = cast(Group, parent_group)
         else:
             group = Group()
             group.set('id', f'inkstitch-tartan-{int(time.time())}')
@@ -86,6 +86,7 @@ class TartanSvgGroup:
         # set outline invisible
         outline.style['display'] = 'none'
         group.append(outline)
+        return group
 
     def _generate_tartan_group_elements(self, group, outline_shape, transform):
         dimensions, rotation_center = self._get_dimensions(outline_shape)
diff --git a/lib/threads/color.py b/lib/threads/color.py
index 58861017..e71ebb06 100644
--- a/lib/threads/color.py
+++ b/lib/threads/color.py
@@ -11,8 +11,6 @@ from pyembroidery.EmbThread import EmbThread
 
 
 class ThreadColor(object):
-    hex_str_re = re.compile('#([0-9a-z]{3}|[0-9a-z]{6})', re.I)
-
     def __init__(self, color, name=None, number=None, manufacturer=None, description=None, chart=None):
         '''
         avoid error messages:
@@ -36,11 +34,9 @@ class ThreadColor(object):
             self.rgb = (color.get_red(), color.get_green(), color.get_blue())
             return
         elif isinstance(color, str):
-            self.rgb = Color.parse_str(color)[1]
+            self.rgb = Color(color).to('rgb').get_values(False)
         elif isinstance(color, (list, tuple)):
             self.rgb = tuple(color)
-        elif self.hex_str_re.match(color):
-            self.rgb = Color.parse_str(color)[1]
         else:
             raise ValueError("Invalid color: " + repr(color))
 
diff --git a/lib/utils/cache.py b/lib/utils/cache.py
index 18f993e9..cca6296a 100644
--- a/lib/utils/cache.py
+++ b/lib/utils/cache.py
@@ -8,16 +8,12 @@ import os
 import pickle
 import sqlite3
 
-import diskcache
+import diskcache  # type: ignore[import-untyped]
 
 from lib.utils.settings import global_settings
 
 from .paths import get_user_dir
-
-try:
-    from functools import lru_cache
-except ImportError:
-    from backports.functools_lru_cache import lru_cache
+from functools import lru_cache
 
 
 # simplify use of lru_cache decorator
diff --git a/lib/utils/param.py b/lib/utils/param.py
index 162dcddc..6def49f7 100644
--- a/lib/utils/param.py
+++ b/lib/utils/param.py
@@ -1,5 +1,5 @@
 class ParamOption:
-    def __init__(self, param_id=None, name=None, preview_image=None):
+    def __init__(self, param_id=None, name=None, preview_image=None) -> None:
         self.id: str = param_id
         self.name: str = name
         self.preview_image: str = preview_image
diff --git a/mypy.ini b/mypy.ini
new file mode 100644
index 00000000..e2563424
--- /dev/null
+++ b/mypy.ini
@@ -0,0 +1,40 @@
+[mypy]
+files = lib/**/*.py,tests/**/*.py
+
+# Some of our code "reuses" variable names in different blocks. Mypy doesn't like that by default.
+allow_redefinition = True
+
+# We use class properties, which mypy considers an error, probably because it's going to be deprecated.
+# Ignore that for now.
+disable_error_code = misc
+
+# A handful of strictness increases we can pass as it is
+warn_unused_configs = True
+warn_redundant_casts = True
+warn_unused_ignores = True
+
+strict_equality = True
+extra_checks = True
+disallow_subclassing_any = True
+disallow_untyped_decorators = True
+
+# An example of increased strictness: We can increase the strictness of parts of the code as we go.
+[mypy-lib.elements.clone]
+check_untyped_defs = True
+disallow_incomplete_defs = True
+disallow_untyped_defs = True
+
+# This part of the code will need some work before it'll start passing.
+[mypy-lib.tartan.*]
+ignore_errors = True
+
+# These libraries are missing type information
+[mypy-colormath2.*]
+ignore_missing_imports = True
+
+[mypy-winutils.*]
+ignore_missing_imports = True
+
+# ... And this one is ours but is missing type information for now anyway...
+[mypy-pyembroidery.*]
+ignore_missing_imports = True
diff --git a/requirements.txt b/requirements.txt
index 84bf40d4..57248c4f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,15 +3,14 @@
 # but the .gitignore file should be updated to ignore the build directory.
 ./pyembroidery
 
-# get up to date inkex version (Febuary 10, 2024)
-inkex @ git+https://gitlab.com/inkscape/extensions.git@618fe5e1e431d4b28a078660bf17afc65335fe39
+# get up to date inkex version (March 1, 2024)
+inkex @ git+https://gitlab.com/inkscape/extensions.git@1792934a09046fdef8aab20d05aad9c47f825bf5
 
 # for linux user it may be tricky to install wxPython from sources
 # prebuilt packages: https://wxpython.org/pages/downloads/index.html
 #                    https://extras.wxpython.org/wxPython4/extras/linux/gtk3/
 wxPython>=4.1.1
 
-backports.functools_lru_cache
 networkx
 shapely>=2.0.0
 lxml
@@ -32,9 +31,16 @@ diskcache
 flask-cors
 pywinutils ; sys_platform == 'win32'
 pywin32 ; sys_platform == 'win32'
+types-pywin32; sys_platform == 'win32'
 
 # Test dependencies.
 # It should be okay to include these here because this list isn't the one used for bundling dependencies.
 # Instead Pyinstaller finds what dependencies the project needs based on what inkstitch.py imports
 pytest
 
+# Misc dev dependencies
+types-wxpython
+types-appdirs
+types-shapely
+types-networkx
+types-lxml
diff --git a/tests/test_clone.py b/tests/test_clone.py
index f089cb43..4b4cf101 100644
--- a/tests/test_clone.py
+++ b/tests/test_clone.py
@@ -23,22 +23,22 @@ def element_fill_angle(element: EmbroideryElement) -> Optional[float]:
 
 class CloneElementTest(TestCase):
     # Monkey-patch the cahce to forcibly disable it: We may need to refactor this out for tests.
-    def setUp(self):
+    def setUp(self) -> None:
         from pytest import MonkeyPatch
         self.monkeypatch = MonkeyPatch()
         self.monkeypatch.setattr(cache_module, "is_cache_disabled", lambda: True)
 
-    def tearDown(self):
+    def tearDown(self) -> None:
         self.monkeypatch.undo()
         return super().tearDown()
 
-    def assertAngleAlmostEqual(self, a, b):
+    def assertAngleAlmostEqual(self, a, b) -> None:
         # Take the mod 180 of the returned angles, because e.g. -130deg and 50deg produce fills along the same angle.
         # We have to use a precision of 4 decimal digits because of the precision of the matrices as they are stored in the svg trees
         # generated by these tests.
         self.assertAlmostEqual(a % 180, b % 180, 4)
 
-    def test_not_embroiderable(self):
+    def test_not_embroiderable(self) -> None:
         root: SvgDocumentElement = svg()
         text = root.add(TextElement())
         text.text = "Can't embroider this!"
@@ -49,7 +49,7 @@ class CloneElementTest(TestCase):
         stitch_groups = clone.to_stitch_groups(None)
         self.assertEqual(len(stitch_groups), 0)
 
-    def test_not_clone(self):
+    def test_not_clone(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -67,7 +67,7 @@ class CloneElementTest(TestCase):
 
     # These tests make sure the element cloning works as expected, using the `clone_elements` method.
 
-    def test_basic(self):
+    def test_basic(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -80,9 +80,9 @@ class CloneElementTest(TestCase):
         clone = Clone(use)
         with clone.clone_elements() as elements:
             self.assertEqual(len(elements), element_count())
-            self.assertAlmostEqual(element_fill_angle(elements[0]), 30)
+            self.assertAngleAlmostEqual(element_fill_angle(elements[0]), 30)
 
-    def test_hidden_cloned_elements_not_embroidered(self):
+    def test_hidden_cloned_elements_not_embroidered(self) -> None:
         root = svg()
         g = root.add(Group())
         g.add(Rectangle(attrib={
@@ -113,7 +113,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(len(elements), element_count())
             self.assertEqual(elements[0].node.get(INKSCAPE_LABEL), "NotHidden")
 
-    def test_angle_rotated(self):
+    def test_angle_rotated(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -129,7 +129,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(len(elements), element_count())
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), 10)
 
-    def test_angle_flipped(self):
+    def test_angle_flipped(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -145,7 +145,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(len(elements), element_count())
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), -30)
 
-    def test_angle_flipped_rotated(self):
+    def test_angle_flipped_rotated(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -162,7 +162,7 @@ class CloneElementTest(TestCase):
             # Fill angle goes from 30 -> -30 after flip -> -50 after rotate
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), -50)
 
-    def test_angle_non_uniform_scale(self):
+    def test_angle_non_uniform_scale(self) -> None:
         """
         The angle isn't *as* well-defined for non-rotational scales, but we try to follow how the slope will be altered.
         """
@@ -183,7 +183,7 @@ class CloneElementTest(TestCase):
             # then rotated another -10 degrees to -55
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), -55)
 
-    def test_angle_inherits_down_tree(self):
+    def test_angle_inherits_down_tree(self) -> None:
         """
         The stitching angle of a clone is based in part on the relative transforms of the source and clone.
         """
@@ -207,7 +207,7 @@ class CloneElementTest(TestCase):
             # Angle goes from 30 -> 40 (g1 -> g2) -> 29 (use)
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), 29)
 
-    def test_angle_not_applied_twice(self):
+    def test_angle_not_applied_twice(self) -> None:
         """Make sure that angle changes are not applied twice to an element with both stroke and fill."""
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
@@ -226,7 +226,7 @@ class CloneElementTest(TestCase):
             # Angle goes from 0 -> -30
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), -30)
 
-    def test_angle_not_applied_to_non_fills(self):
+    def test_angle_not_applied_to_non_fills(self) -> None:
         """Make sure that angle changes are not applied to non-fill elements."""
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
@@ -243,7 +243,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(len(elements), element_count())  # One for the stroke, one for the fill, one for the SewStack
             self.assertIsNone(elements[0].get_param("angle", None))  # Angle as not set, as this isn't a fill
 
-    def test_style_inherits(self):
+    def test_style_inherits(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -262,7 +262,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(style["stroke"], "skyblue")
             self.assertEqual(style["stroke-width"], "2")
 
-    def test_transform_inherits_from_cloned_element(self):
+    def test_transform_inherits_from_cloned_element(self) -> None:
         """
         Elements cloned by cloned_elements need to inherit their transform from their href'd element and their use to match what's shown.
         """
@@ -284,7 +284,7 @@ class CloneElementTest(TestCase):
                 elements[0].node.composed_transform(),
                 Transform().add_translate((5, 10)).add_scale(2, 2))
 
-    def test_transform_inherits_from_tree(self):
+    def test_transform_inherits_from_tree(self) -> None:
         root: SvgDocumentElement = svg()
         g1 = root.add(Group())
         g1.set('transform', Transform().add_translate((0, 5)).add_rotate(5))
@@ -308,7 +308,7 @@ class CloneElementTest(TestCase):
                 .add_scale(2, 2),  # rect
                 5)
 
-    def test_transform_inherits_from_tree_up_tree(self):
+    def test_transform_inherits_from_tree_up_tree(self) -> None:
         root: SvgDocumentElement = svg()
         g1 = root.add(Group())
         g1.set('transform', Transform().add_translate((0, 5)).add_rotate(5))
@@ -343,7 +343,7 @@ class CloneElementTest(TestCase):
                 .add_translate((0, 5)).add_rotate(5),  # g1
                 5)
 
-    def test_clone_fill_angle_not_specified(self):
+    def test_clone_fill_angle_not_specified(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -357,7 +357,7 @@ class CloneElementTest(TestCase):
         clone = Clone(use)
         self.assertEqual(clone.clone_fill_angle, None)
 
-    def test_clone_fill_angle(self):
+    def test_clone_fill_angle(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -376,7 +376,7 @@ class CloneElementTest(TestCase):
             self.assertEqual(len(elements), element_count())
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), 42)
 
-    def test_angle_manually_flipped(self):
+    def test_angle_manually_flipped(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -396,7 +396,7 @@ class CloneElementTest(TestCase):
 
     # Recursive use tests
 
-    def test_recursive_uses(self):
+    def test_recursive_uses(self) -> None:
         root: SvgDocumentElement = svg()
         g1 = root.add(Group())
         rect = g1.add(Rectangle(attrib={
@@ -433,7 +433,7 @@ class CloneElementTest(TestCase):
                                       .add_translate((20, 0))  # u1
                                       )
 
-    def test_recursive_uses_angle(self):
+    def test_recursive_uses_angle(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -482,7 +482,7 @@ class CloneElementTest(TestCase):
             # Angle goes from -30 -> -37
             self.assertAngleAlmostEqual(element_fill_angle(elements[0]), -37)
 
-    def test_recursive_uses_angle_with_specified_angle(self):
+    def test_recursive_uses_angle_with_specified_angle(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -510,7 +510,7 @@ class CloneElementTest(TestCase):
 
     # Command clone tests
 
-    def test_copies_directly_attached_commands(self):
+    def test_copies_directly_attached_commands(self) -> None:
         """
         Check that commands attached to the clone target directly are applied to clones.
         """
@@ -536,7 +536,7 @@ class CloneElementTest(TestCase):
             self.assertAlmostEqual(cmd_orig.target_point[0]+10, cmd_clone.target_point[0], 4)
             self.assertAlmostEqual(cmd_orig.target_point[1]+10, cmd_clone.target_point[1], 4)
 
-    def test_copies_indirectly_attached_commands(self):
+    def test_copies_indirectly_attached_commands(self) -> None:
         """
         Check that commands attached to children of the clone target are copied to clones.
         """
@@ -565,7 +565,7 @@ class CloneElementTest(TestCase):
 
     # Checks that trim_after and stop_after commands and settings in cloned elements aren't overridden
 
-    def test_trim_after(self):
+    def test_trim_after(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -582,7 +582,7 @@ class CloneElementTest(TestCase):
         self.assertGreater(len(stitch_groups), 0)
         self.assertTrue(stitch_groups[-1].trim_after)
 
-    def test_trim_after_command(self):
+    def test_trim_after_command(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -599,7 +599,7 @@ class CloneElementTest(TestCase):
         self.assertGreater(len(stitch_groups), 0)
         self.assertTrue(stitch_groups[-1].trim_after)
 
-    def test_trim_after_command_on_clone(self):
+    def test_trim_after_command_on_clone(self) -> None:
         """
         If the clone element has a trim command, it should apply!
         """
@@ -619,7 +619,7 @@ class CloneElementTest(TestCase):
         self.assertGreater(len(stitch_groups), 0)
         self.assertTrue(stitch_groups[-1].trim_after)
 
-    def test_stop_after(self):
+    def test_stop_after(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -636,7 +636,7 @@ class CloneElementTest(TestCase):
         self.assertGreater(len(stitch_groups), 0)
         self.assertTrue(stitch_groups[-1].stop_after)
 
-    def test_stop_after_command(self):
+    def test_stop_after_command(self) -> None:
         root: SvgDocumentElement = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -654,7 +654,7 @@ class CloneElementTest(TestCase):
         self.assertGreater(len(stitch_groups), 0)
         self.assertTrue(stitch_groups[-1].stop_after)
 
-    def test_stop_after_command_on_clone(self):
+    def test_stop_after_command_on_clone(self) -> None:
         """
         If the clone element has a stop command, it should still apply!
         """
diff --git a/tests/test_elements_utils.py b/tests/test_elements_utils.py
index 4653ac69..2c0a64eb 100644
--- a/tests/test_elements_utils.py
+++ b/tests/test_elements_utils.py
@@ -10,7 +10,7 @@ from .utils import element_count
 class ElementsUtilsTest(TestCase):
     # These tests test two functions at once, but they're sort of complimentary.
     # Might suggest that they could be combined in a later refactor?
-    def test_iterate_nodes_to_elements(self):
+    def test_iterate_nodes_to_elements(self) -> None:
         root = svg()
         g = root.add(Group())
         rect = g.add(Rectangle(attrib={
@@ -35,7 +35,7 @@ class ElementsUtilsTest(TestCase):
         self.assertEqual(type(elements[0]), FillStitch)
         self.assertEqual(elements[0].node, rect)
 
-    def test_iterate_nodes_to_elements_root_embroiderable(self):
+    def test_iterate_nodes_to_elements_root_embroiderable(self) -> None:
         """ Case where the root node is directly embroiderable """
         root = svg()
         rect = root.add(Rectangle(attrib={
diff --git a/tests/test_lib_svg_svg.py b/tests/test_lib_svg_svg.py
index 1d873fb2..825715d6 100644
--- a/tests/test_lib_svg_svg.py
+++ b/tests/test_lib_svg_svg.py
@@ -6,7 +6,7 @@ from inkex.tester.svg import svg
 
 
 class LibSvgSvgTest(TestCase):
-    def test_point_upwards(self):
+    def test_point_upwards(self) -> None:
         root = svg()
         rect = root.add(Rectangle(attrib={
             "width": "10",
@@ -24,7 +24,7 @@ class LibSvgSvgTest(TestCase):
             4
         )
 
-    def test_point_upwards_mirrored(self):
+    def test_point_upwards_mirrored(self) -> None:
         root = svg()
         rect = root.add(PathElement(attrib={
             "d": "M 0,0 L 10,0 0,5 Z",