diff --git a/novelwriter/__init__.py b/novelwriter/__init__.py
index 6f6fc63e..2eb80148 100644
--- a/novelwriter/__init__.py
+++ b/novelwriter/__init__.py
@@ -254,11 +254,13 @@ def main(sysArgs: list | None = None) -> GuiMain | None:
             pass  # Quietly ignore error
 
     # Import GUI (after dependency checks), and launch
+    from novelwriter.gui.theme import GuiTheme
     from novelwriter.guimain import GuiMain
 
     if testMode:
         # Only used for testing where the test framework creates the app
         CONFIG.loadConfig()
+        SHARED.initTheme(GuiTheme())
         return GuiMain()
 
     app = QApplication([CONFIG.appName, (f"-style={qtStyle}")])
@@ -274,6 +276,7 @@ def main(sysArgs: list | None = None) -> GuiMain | None:
     # Run Config steps that require the QApplication
     CONFIG.loadConfig()
     CONFIG.initLocalisation(app)
+    SHARED.initTheme(GuiTheme())
 
     # Launch main GUI
     nwGUI = GuiMain()
diff --git a/novelwriter/extensions/switch.py b/novelwriter/extensions/switch.py
index 9ee155a7..2b320506 100644
--- a/novelwriter/extensions/switch.py
+++ b/novelwriter/extensions/switch.py
@@ -98,14 +98,14 @@ class NSwitch(QAbstractButton):
             trackBrush = palette.highlight()
             thumbBrush = palette.highlightedText()
         else:
-            trackBrush = palette.dark()
+            trackBrush = palette.mid()
             thumbBrush = palette.light()
 
         if self.isEnabled():
             trackOpacity = 1.0
         else:
             trackOpacity = 0.6
-            trackBrush = palette.shadow()
+            trackBrush = palette.dark()
             thumbBrush = palette.mid()
 
         painter.setBrush(trackBrush)
@@ -114,6 +114,7 @@ class NSwitch(QAbstractButton):
 
         painter.setBrush(thumbBrush)
         painter.drawEllipse(self._offset - self._rR, self._rB, self._rH, self._rH)
+        painter.end()
 
         return
 
diff --git a/novelwriter/gui/theme.py b/novelwriter/gui/theme.py
index 9093bb8f..98efd50b 100644
--- a/novelwriter/gui/theme.py
+++ b/novelwriter/gui/theme.py
@@ -304,6 +304,20 @@ class GuiTheme:
         backCol = self._guiPalette.window().color()
         textCol = self._guiPalette.windowText().color()
 
+        # Calculate Based on Qt Fusion
+        light    = backCol.lighter(150)
+        mid      = backCol.darker(130)
+        midLight = mid.lighter(110)
+        dark     = backCol.darker(150)
+        shadow   = dark.darker(135)
+
+        self._guiPalette.setColor(QPalette.ColorRole.Light,    light)
+        self._guiPalette.setColor(QPalette.ColorRole.Mid,      mid)
+        self._guiPalette.setColor(QPalette.ColorRole.Midlight, midLight)
+        self._guiPalette.setColor(QPalette.ColorRole.Dark,     dark)
+        self._guiPalette.setColor(QPalette.ColorRole.Shadow,   shadow)
+
+        # Calculate Help Text
         backLNess = backCol.lightnessF()
         textLNess = textCol.lightnessF()
         self.isLightTheme = backLNess > textLNess
diff --git a/novelwriter/guimain.py b/novelwriter/guimain.py
index 9e10e3f3..56e17517 100644
--- a/novelwriter/guimain.py
+++ b/novelwriter/guimain.py
@@ -56,7 +56,6 @@ from novelwriter.gui.projtree import GuiProjectView
 from novelwriter.gui.search import GuiProjectSearch
 from novelwriter.gui.sidebar import GuiSideBar
 from novelwriter.gui.statusbar import GuiMainStatus
-from novelwriter.gui.theme import GuiTheme
 from novelwriter.tools.dictionaries import GuiDictionaries
 from novelwriter.tools.manuscript import GuiManuscript
 from novelwriter.tools.noveldetails import GuiNovelDetails
@@ -101,7 +100,7 @@ class GuiMain(QMainWindow):
         # ============
 
         # Initialise UserData Instance
-        SHARED.initSharedData(self, GuiTheme())
+        SHARED.initSharedData(self)
 
         # Prepare Main Window
         self.resize(*CONFIG.mainWinSize)
@@ -1054,6 +1053,7 @@ class GuiMain(QMainWindow):
             # We are doing this manually instead of connecting to
             # paletteChanged since the processing order matters
             SHARED.theme.loadTheme()
+            self.setPalette(QApplication.palette())
             self.docEditor.updateTheme()
             self.docViewer.updateTheme()
             self.docViewerPanel.updateTheme()
diff --git a/novelwriter/shared.py b/novelwriter/shared.py
index 2fd5359c..588252d9 100644
--- a/novelwriter/shared.py
+++ b/novelwriter/shared.py
@@ -164,17 +164,24 @@ class SharedData(QObject):
     #  Methods
     ##
 
-    def initSharedData(self, gui: GuiMain, theme: GuiTheme) -> None:
+    def initTheme(self, theme: GuiTheme) -> None:
+        """Initialise the GUI theme. This must be called before the GUI
+        is created.
+        """
+        self._theme = theme
+        return
+
+    def initSharedData(self, gui: GuiMain) -> None:
         """Initialise the SharedData instance. This must be called as
         soon as the Main GUI is created to ensure the SHARED singleton
         has the properties needed for operation.
         """
         self._clock.start()
         self._gui = gui
-        self._theme = theme
         self._resetProject()
         logger.debug("Ready: SharedData")
-        logger.debug("Thread Pool Max Count: %d", QThreadPool.globalInstance().maxThreadCount())
+        if pool := QThreadPool.globalInstance():
+            logger.debug("Thread Pool Max Count: %d", pool.maxThreadCount())
         return
 
     def closeDocument(self, tHandle: str | None = None) -> None:
@@ -266,7 +273,8 @@ class SharedData(QObject):
 
     def runInThreadPool(self, runnable: QRunnable, priority: int = 0) -> None:
         """Queue a runnable in the application thread pool."""
-        QThreadPool.globalInstance().start(runnable, priority=priority)
+        if pool := QThreadPool.globalInstance():
+            pool.start(runnable, priority=priority)
         return
 
     def getProjectPath(
@@ -278,13 +286,13 @@ class SharedData(QObject):
         label = (self.tr("novelWriter Project File or Zip File")
                  if allowZip else self.tr("novelWriter Project File"))
         ext = f"{nwFiles.PROJ_FILE} *.zip" if allowZip else nwFiles.PROJ_FILE
-        ffilter = formatFileFilter([(label, ext), "*"])
+        fFilter = formatFileFilter([(label, ext), "*"])
         selected, _ = QFileDialog.getOpenFileName(
-            parent, self.tr("Open Project"), str(path or ""), filter=ffilter
+            parent, self.tr("Open Project"), str(path or ""), filter=fFilter
         )
         return Path(selected) if selected else None
 
-    def getFont(self, current: QFont, native: bool) -> tuple[QFont, bool]:
+    def getFont(self, current: QFont, native: bool) -> tuple[QFont, bool | None]:
         """Open the font dialog and select a font."""
         kwargs = {}
         if not native:
diff --git a/tests/conftest.py b/tests/conftest.py
index 5ffebaa7..0c7541d2 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -33,7 +33,7 @@ from PyQt6.QtWidgets import QMessageBox
 
 sys.path.insert(1, str(Path(__file__).parent.parent.absolute()))
 
-from novelwriter import CONFIG, SHARED, main  # noqa: E402
+from novelwriter import CONFIG, SHARED  # noqa: E402
 
 from tests.mocked import MockGuiMain, MockTheme  # noqa: E402
 from tests.tools import cleanProject  # noqa: E402
@@ -160,11 +160,15 @@ def mockGUI(qtbot, monkeypatch):
 @pytest.fixture(scope="function")
 def nwGUI(qtbot, monkeypatch, functionFixture):
     """Create an instance of the novelWriter GUI."""
+    from novelwriter.gui.theme import GuiTheme
+    from novelwriter.guimain import GuiMain
+
     monkeypatch.setattr(QMessageBox, "exec", lambda *a: None)
     monkeypatch.setattr(QMessageBox, "result", lambda *a: QMessageBox.StandardButton.Yes)
 
-    nwGUI = main(["--testmode", f"--config={_TMP_CONF}", f"--data={_TMP_CONF}"])
-    assert nwGUI is not None
+    CONFIG.loadConfig()
+    SHARED.initTheme(GuiTheme())
+    nwGUI = GuiMain()
     qtbot.addWidget(nwGUI)
     resetConfigVars()
     nwGUI.docEditor.initEditor()
diff --git a/tests/test_base/test_base_shared.py b/tests/test_base/test_base_shared.py
index 85a8200a..4f147b2b 100644
--- a/tests/test_base/test_base_shared.py
+++ b/tests/test_base/test_base_shared.py
@@ -56,7 +56,8 @@ def testBaseSharedData_Init():
     assert mockGui is not mockTheme
 
     # Properly initialise the class
-    shared.initSharedData(mockGui, mockTheme)  # type: ignore
+    shared.initTheme(mockTheme)  # type: ignore
+    shared.initSharedData(mockGui)  # type: ignore
 
     assert shared.mainGui is mockGui
     assert shared.theme is mockTheme
@@ -94,7 +95,8 @@ def testBaseSharedData_Projects(monkeypatch, caplog, fncPath):
     # Initialise the instance, should create an empty project
     mockGui = MockGuiMain()
     mockTheme = MockTheme()
-    shared.initSharedData(mockGui, mockTheme)  # type: ignore
+    shared.initTheme(mockTheme)  # type: ignore
+    shared.initSharedData(mockGui)  # type: ignore
     assert isinstance(shared.project, NWProject)
     assert shared.hasProject is False
 
@@ -150,7 +152,8 @@ def testBaseSharedData_Alerts(qtbot, monkeypatch, caplog):
 
     mockGui = MockGuiMain()
     mockTheme = MockTheme()
-    shared.initSharedData(mockGui, mockTheme)  # type: ignore
+    shared.initTheme(mockTheme)  # type: ignore
+    shared.initSharedData(mockGui)  # type: ignore
 
     assert shared.lastAlert == ""