ENH: Refactor HomeWidget to support custom toolbars

Improves the HomeWidget class by introducing a more flexible and scalable
approach to managing custom toolbars in the application:

- Adds toolbarNames property to dynamically manage toolbar names
- Refactors the modifyWindowUI method to create and manage multiple
  custom toolbars, introducing the following functions:
  - `initializeAppToolBar`: Creates a parent toolbar for the application.
  - `addToolBar`: Helper method to initialize and parent new custom toolbars to the application toolbar.
  - `initializeSettingsToolBar`: Creates the settings toolbar with the gear icon button to toggle
    visibility of the settings dialog.

{{cookiecutter.project_name}}/.ruff.toml

@@ -54,6 +54,7 @@ extend-ignore = [
   "Q003",
   "W191",
 ]
+
 flake8-annotations.suppress-dummy-args = true
 flake8-annotations.suppress-none-returning = true
 isort.known-third-party = [
@@ -69,3 +70,8 @@ isort.known-first-party = [
   "Resources",
 ]
 pydocstyle.convention = "pep257"
+
+[lint.per-file-ignores]
+# To conveniently support declaring instance variable in the HomeWidget
+# class, disable "RUF012: Mutable class attributes should be annotated"
+"Modules/Scripted/Home/Home.py" = ["RUF012"]

{{cookiecutter.project_name}}/Modules/Scripted/Home/Home.py

@@ -1,4 +1,5 @@
-from typing import Optional
+from collections.abc import Mapping
+from typing import Final, Optional
 
 import qt
 import slicer
@@ -39,6 +40,15 @@ class HomeWidget(ScriptedLoadableModuleWidget, VTKObservationMixin):
     https://github.com/Slicer/Slicer/blob/main/Base/Python/slicer/ScriptedLoadableModule.py
     """
 
+    APP_TOOLBAR_NAME: Final[str] = "appToolBar"
+
+    @property
+    def toolbarNames(self) -> list[str]:
+        return [str(k) for k in self._toolbars]
+
+    # Members
+    _toolbars: Mapping[str, qt.QToolBar] = {}
+
     def __init__(self, parent: Optional[qt.QWidget]):
         """Called when the application opens the module the first time and the widget is initialized."""
         ScriptedLoadableModuleWidget.__init__(self, parent)
@@ -77,7 +87,7 @@ def setSlicerUIVisible(self, visible: bool):
         exemptToolbars = [
             "MainToolBar",
             "ViewToolBar",
-            "CustomToolBar",
+            *self.toolbarNames,
         ]
         slicer.util.setDataProbeVisible(visible)
         slicer.util.setMenuBarsVisible(visible, ignore=exemptToolbars)
@@ -89,15 +99,38 @@ def setSlicerUIVisible(self, visible: bool):
         slicer.util.setToolbarsVisible(visible, keepToolbars)
 
     def modifyWindowUI(self):
-        # Custom toolbar
+        """Customize the entire user interface to resemble the custom application"""
+        # Custom toolbars
+        self.initializeAppToolBar()
+        self.initializeSettingsToolBar()
+
+    def initializeAppToolBar(self):
+        """Create parent toolbar for the application"""
+        appToolBar = qt.QToolBar(HomeWidget.APP_TOOLBAR_NAME)
+        appToolBar.name = HomeWidget.APP_TOOLBAR_NAME
+        appToolBar.setMovable(False)
+        appToolBar.setFloatable(False)
         mainToolBar = slicer.util.findChild(slicer.util.mainWindow(), "MainToolBar")
-        self.CustomToolBar = qt.QToolBar("CustomToolBar")
-        self.CustomToolBar.name = "CustomToolBar"
-        slicer.util.mainWindow().insertToolBar(mainToolBar, self.CustomToolBar)
+        slicer.util.mainWindow().insertToolBar(mainToolBar, appToolBar)
+        self._toolbars[appToolBar.name] = appToolBar
+
+    def addToolBar(self, toolBarName: str) -> qt.QToolBar:
+        """Helper method to initialize a new custom toolbar and parent it to the application toolbar"""
+        self._toolbars[toolBarName] = qt.QToolBar(toolBarName)
+        self._toolbars[toolBarName].name = toolBarName
+        self._toolbars[toolBarName].setMovable(False)
+        self._toolbars[toolBarName].setFloatable(False)
+        slicer.util.mainWindow().insertToolBar(self._toolbars[HomeWidget.APP_TOOLBAR_NAME], self._toolbars[toolBarName])
+        return self._toolbars[toolBarName]
+
+    def initializeSettingsToolBar(self):
+        """Create toolbar and dialog for app settings"""
+        settingsToolBar = self.addToolBar("SettingsToolBar")
 
-        # Settings dialog
         gearIcon = qt.QIcon(self.resourcePath("Icons/Gears.png"))
-        self.settingsAction = self.CustomToolBar.addAction(gearIcon, "")
+        self.settingsAction = settingsToolBar.addAction(gearIcon, "")
+
+        # Settings dialog
         self.settingsDialog = slicer.util.loadUI(self.resourcePath("UI/Settings.ui"))
         self.settingsUI = slicer.util.childWidgetVariables(self.settingsDialog)
         self.settingsUI.CustomUICheckBox.toggled.connect(self.setCustomUIVisible)