diff --git a/novelwriter/core/buildsettings.py b/novelwriter/core/buildsettings.py
index cc4b3df1..5a04f00b 100644
--- a/novelwriter/core/buildsettings.py
+++ b/novelwriter/core/buildsettings.py
@@ -1,7 +1,6 @@
 """
-novelWriter – Build Settings Class
-==================================
-A class to hold build settings for the build tool
+novelWriter – Build Settings
+============================
 
 File History:
 Created: 2023-02-14 [2.1b1] BuildSettings
@@ -117,6 +116,7 @@ SETTINGS_LABELS = {
 
 
 class FilterMode(Enum):
+    """The decision reason for an item in a filtered project."""
 
     UNKNOWN  = 0
     FILTERED = 1
@@ -128,6 +128,11 @@ class FilterMode(Enum):
 
 
 class BuildSettings:
+    """Core: Build Settings Class
+
+    This class manages the build settings for a Manuscript build job.
+    The settings can be packed/unpacked to/from a dictionary for JSON.
+    """
 
     def __init__(self):
         self._name = ""
@@ -145,14 +150,17 @@ class BuildSettings:
 
     @property
     def name(self) -> str:
+        """Return the build name."""
         return self._name
 
     @property
     def buildID(self) -> str:
+        """Return the build ID."""
         return self._uuid
 
     @property
     def changed(self) -> bool:
+        """Return the changed status of the build."""
         return self._changed
 
     ##
@@ -161,33 +169,28 @@ class BuildSettings:
 
     @staticmethod
     def getLabel(key: str) -> str:
-        """Extract the label for a specific item.
-        """
+        """Extract the GUI label for a specific setting."""
         return SETTINGS_LABELS.get(key, "ERROR")
 
     def getStr(self, key: str) -> str:
-        """Type safe value access for strings.
-        """
+        """Type safe value access for strings."""
         value = self._settings.get(key, SETTINGS_TEMPLATE.get(key, (None, None)[1]))
         return str(value)
 
     def getBool(self, key: str) -> bool:
-        """Type safe value access for bools.
-        """
+        """Type safe value access for bools."""
         value = self._settings.get(key, SETTINGS_TEMPLATE.get(key, (None, None)[1]))
         return bool(value)
 
     def getInt(self, key: str) -> int:
-        """Type safe value access for integers.
-        """
+        """Type safe value access for integers."""
         value = self._settings.get(key, SETTINGS_TEMPLATE.get(key, (None, None)[1]))
         if isinstance(value, int):
             return value
         return 0
 
     def getFloat(self, key: str) -> float:
-        """Type safe value access for float.
-        """
+        """Type safe value access for float."""
         value = self._settings.get(key, SETTINGS_TEMPLATE.get(key, (None, None)[1]))
         if isinstance(value, float):
             return value
@@ -198,14 +201,12 @@ class BuildSettings:
     ##
 
     def setName(self, name: str):
-        """Set the build setting display name.
-        """
+        """Set the build setting display name."""
         self._name = str(name)
         return
 
     def setBuildID(self, value: str | uuid.UUID):
-        """Set a UUID build ID.
-        """
+        """Set a UUID build ID."""
         value = checkUuid(value, "")
         if not value:
             self._uuid = str(uuid.uuid4())
@@ -214,32 +215,28 @@ class BuildSettings:
         return
 
     def setFiltered(self, tHandle: str):
-        """Set an item as filtered.
-        """
+        """Set an item as filtered."""
         self._excluded.discard(tHandle)
         self._included.discard(tHandle)
         self._changed = True
         return
 
     def setIncluded(self, tHandle: str):
-        """Set an item as explicitly included.
-        """
+        """Set an item as explicitly included."""
         self._excluded.discard(tHandle)
         self._included.add(tHandle)
         self._changed = True
         return
 
     def setExcluded(self, tHandle: str):
-        """Set an item as explicitly excluded.
-        """
+        """Set an item as explicitly excluded."""
         self._excluded.add(tHandle)
         self._included.discard(tHandle)
         self._changed = True
         return
 
     def setSkipRoot(self, tHandle: str, state: bool):
-        """Set a specific root folder as skipped or not.
-        """
+        """Set a specific root folder as skipped or not."""
         if state is True:
             self._skipRoot.discard(tHandle)
             self._changed = True
@@ -249,8 +246,7 @@ class BuildSettings:
         return
 
     def setValue(self, key: str, value: str | int | bool | float) -> bool:
-        """Set a specific value for a build setting.
-        """
+        """Set a specific value for a build setting."""
         if key not in SETTINGS_TEMPLATE:
             return False
         definition = SETTINGS_TEMPLATE[key]
@@ -267,19 +263,11 @@ class BuildSettings:
     #  Methods
     ##
 
-    def isFiltered(self, tHandle: str) -> bool:
-        return tHandle not in self._included and tHandle not in self._excluded
-
-    def isIncluded(self, tHandle: str) -> bool:
-        return tHandle in self._included
-
-    def isExcluded(self, tHandle: str) -> bool:
-        return tHandle in self._excluded
-
     def isRootAllowed(self, tHandle: str) -> bool:
+        """Check if a root handle is allowed in the build."""
         return tHandle not in self._skipRoot
 
-    def buildItemFilter(self, project: NWProject) -> dict:
+    def buildItemFilter(self, project: NWProject) -> dict[str, tuple[bool, FilterMode]]:
         """Return a dictionary of item handles with filter decissions
         applied.
         """
@@ -325,15 +313,14 @@ class BuildSettings:
         return result
 
     def resetChangedState(self):
-        """This must be called when the changes to this class has been
-        safely saved to file or passed on.
+        """Reset the changed status of the settings object. This must be
+        called when the changes have been safely saved or passed on.
         """
         self._changed = False
         return
 
     def pack(self) -> dict:
-        """Pack all content into a JSON compatible dictionary.
-        """
+        """Pack all content into a JSON compatible dictionary."""
         logger.debug("Collecting build setting for '%s'", self._name)
         return {
             "name": self._name,
@@ -347,8 +334,7 @@ class BuildSettings:
         }
 
     def unpack(self, data: dict):
-        """Unpack a dictionary and populate the class.
-        """
+        """Unpack a dictionary and populate the class."""
         settings = data.get("settings", {})
         content  = data.get("content", {})
         included = content.get("included", [])
@@ -377,6 +363,12 @@ class BuildSettings:
 
 
 class BuildCollection:
+    """Core: Build Collection Class
+
+    This object holds all the build setting objects defined by the given
+    project. The build settings are saved as a single JSON file in the
+    project folder.
+    """
 
     def __init__(self, project: NWProject):
         self._project = project
@@ -384,8 +376,7 @@ class BuildCollection:
         return
 
     def getBuild(self, buildID: str) -> BuildSettings | None:
-        """Get a specific build settings object.
-        """
+        """Get a specific build settings object."""
         if buildID not in self._builds:
             return None
         build = BuildSettings()
@@ -393,8 +384,7 @@ class BuildCollection:
         return build
 
     def setBuild(self, build: BuildSettings) -> bool:
-        """Set build settings data in the collection.
-        """
+        """Set build settings data in the collection."""
         if not isinstance(build, BuildSettings):
             return False
         buildID = build.buildID
@@ -402,15 +392,13 @@ class BuildCollection:
         return True
 
     def builds(self) -> Iterable[tuple[str, str]]:
-        """Iterate over all avaiable builds.
-        """
+        """Iterate over all avaiable builds."""
         for buildID in self._builds:
             yield buildID, self._builds[buildID].get("name", "")
         return
 
     def loadCollection(self) -> bool:
-        """Load build collections file.
-        """
+        """Load build collections file."""
         buildsFile = self._project.storage.getMetaFile(nwFiles.BUILDS_FILE)
         if not isinstance(buildsFile, Path):
             return False
@@ -442,8 +430,7 @@ class BuildCollection:
         return True
 
     def saveCollection(self) -> bool:
-        """Save build collections file.
-        """
+        """Save build collections file."""
         buildsFile = self._project.storage.getMetaFile(nwFiles.BUILDS_FILE)
         if not isinstance(buildsFile, Path):
             return False
diff --git a/novelwriter/core/docbuild.py b/novelwriter/core/docbuild.py
index b946d20f..2270f708 100644
--- a/novelwriter/core/docbuild.py
+++ b/novelwriter/core/docbuild.py
@@ -1,10 +1,9 @@
 """
-novelWriter – Build Document Tool
-=================================
-A class to build one or more novelWriter files to a single document
+novelWriter – Manuscript Document Builder
+=========================================
 
 File History:
-Created: 2022-12-01 [2.1b1]
+Created: 2022-12-01 [2.1b1] NWBuildDocument
 
 This file is a part of novelWriter
 Copyright 2018–2023, Veronica Berglyd Olsen
@@ -44,6 +43,11 @@ logger = logging.getLogger(__name__)
 
 
 class NWBuildDocument:
+    """Core: Manuscript Document Build Class
+
+    This is the core tool that assembles a project and outputs a
+    manuscript, based on a build definition object (BuildSettings).
+    """
 
     __slots__ = ("_project", "_build", "_queue", "_error", "_cache")
 
@@ -61,10 +65,15 @@ class NWBuildDocument:
 
     @property
     def error(self) -> str | None:
+        """Return the last error, if any."""
         return self._error
 
     @property
     def lastBuild(self) -> Tokenizer | None:
+        """Return the build object of the last build process, if any.
+        This is useful for accessing build details and data after the
+        build job is completed.
+        """
         return self._cache
 
     ##
@@ -72,6 +81,7 @@ class NWBuildDocument:
     ##
 
     def __len__(self) -> int:
+        """Return the length of the build queue."""
         return len(self._queue)
 
     ##
@@ -79,17 +89,17 @@ class NWBuildDocument:
     ##
 
     def addDocument(self, tHandle: str):
-        """Add a document to the build queue manually.
-        """
+        """Add a document to the build queue manually."""
         self._queue.append(tHandle)
         return
 
     def queueAll(self):
-        """Queue all document as defined by the build setup.
-        """
+        """Queue all document as defined by the build settings."""
         filtered = self._build.buildItemFilter(self._project)
         noteTitles = self._build.getBool("text.addNoteHeadings")
         for item in self._project.tree:
+            if not item.itemHandle:
+                continue
             if filtered.get(item.itemHandle, False):
                 self._queue.append(item.itemHandle)
             elif item.isRootType() and noteTitles:
@@ -97,8 +107,7 @@ class NWBuildDocument:
         return
 
     def iterBuildOpenDocument(self, path: Path, isFlat: bool) -> Iterable[tuple[int, bool]]:
-        """Build an Open Document file.
-        """
+        """Build an Open Document file."""
         makeOdt = ToOdt(self._project, isFlat=isFlat)
         self._setupBuild(makeOdt)
         makeOdt.initDocument()
@@ -146,8 +155,7 @@ class NWBuildDocument:
         return
 
     def iterBuildMarkdown(self, path: Path, extendedMd: bool) -> Iterable[tuple[int, bool]]:
-        """Build a Markdown file.
-        """
+        """Build a Markdown file."""
         makeMd = ToMarkdown(self._project)
         self._setupBuild(makeMd)
 
@@ -177,8 +185,7 @@ class NWBuildDocument:
     ##
 
     def _setupBuild(self, bldObj: Tokenizer):
-        """Configure the build object.
-        """
+        """Configure the build object."""
         # Get Settings
         fmtTitle      = self._build.getStr("headings.fmtTitle")
         fmtChapter    = self._build.getStr("headings.fmtChapter")
@@ -240,8 +247,7 @@ class NWBuildDocument:
         return
 
     def _doBuild(self, bldObj: Tokenizer, tHandle: str) -> bool:
-        """Build a single document and add it to the build object.
-        """
+        """Build a single document and add it to the build object."""
         self._error = None
         tItem = self._project.tree[tHandle]
         if tItem is None:
diff --git a/novelwriter/guimain.py b/novelwriter/guimain.py
index d3c5a5cc..f2922b24 100644
--- a/novelwriter/guimain.py
+++ b/novelwriter/guimain.py
@@ -1,10 +1,9 @@
 """
 novelWriter – GUI Main Window
 =============================
-The main application window
 
 File History:
-Created: 2018-09-22 [0.0.1]
+Created: 2018-09-22 [0.0.1] GuiMain
 
 This file is a part of novelWriter
 Copyright 2018–2023, Veronica Berglyd Olsen
@@ -74,6 +73,24 @@ logger = logging.getLogger(__name__)
 
 
 class GuiMain(QMainWindow):
+    """Main GUI Window
+
+    The Main GUI window class. It is the entry point of the
+    application, and holds all runtime objects aside from the main
+    Config instance, which is created before the Main GUI.
+
+    The Main GUI is split up into GUI components, assembled in the init
+    function. Also, the project instance and theme instance are created
+    here. These should be passed around to all other objects who need
+    them and new instances of them should generally not be created.
+
+      * All other GUI classes that depend on any components from the
+        main GUI should be passed a reference to the instance of this
+        class.
+      * All non-GUI classes can be passed a reference to the NWProject
+        instance if the Main GUI is not needed (which it generally
+        shouldn't need).
+    """
 
     def __init__(self):
         super().__init__()
diff --git a/novelwriter/tools/manusbuild.py b/novelwriter/tools/manusbuild.py
index dbb07607..199dbf7f 100644
--- a/novelwriter/tools/manusbuild.py
+++ b/novelwriter/tools/manusbuild.py
@@ -1,10 +1,9 @@
 """
 novelWriter – GUI Build Manuscript
 ==================================
-GUI classes for the Manuscript Build Tool
 
 File History:
-Created: 2023-05-24 [2.1b1]
+Created: 2023-05-24 [2.1b1] GuiManuscriptBuild
 
 This file is a part of novelWriter
 Copyright 2018–2023, Veronica Berglyd Olsen
@@ -32,6 +31,11 @@ logger = logging.getLogger(__name__)
 
 
 class GuiManuscriptBuild(QDialog):
+    """GUI Tools: Manucript Builder Dialog
+
+    This is the tool for running the build itself. It can be accessed
+    independently of the Manuscript Build Tool.
+    """
 
     def __init__(self, parent: QWidget):
         super().__init__(parent=parent)
@@ -46,6 +50,7 @@ class GuiManuscriptBuild(QDialog):
         return
 
     def __del__(self):
+        """For debug use only."""
         logger.debug("Delete: GuiManuscriptBuild")
         return
 
diff --git a/novelwriter/tools/manuscript.py b/novelwriter/tools/manuscript.py
index 33e1be9f..f8ed9d34 100644
--- a/novelwriter/tools/manuscript.py
+++ b/novelwriter/tools/manuscript.py
@@ -1,11 +1,9 @@
 """
-novelWriter – GUI Build Manuscript
-==================================
-GUI classes for the Manuscript Build Tool
+novelWriter – GUI Manuscript Tool
+=================================
 
 File History:
 Created: 2023-05-13 [2.1b1] GuiManuscript
-Created: 2023-05-13 [2.1b1] GuiManuscriptPreview
 
 This file is a part of novelWriter
 Copyright 2018–2023, Veronica Berglyd Olsen
@@ -52,6 +50,12 @@ logger = logging.getLogger(__name__)
 
 
 class GuiManuscript(QDialog):
+    """GUI Tools: Manuscript Tool
+
+    The dialog displays all the users build definitions, a preview panel
+    for the manuscript, and can trigger the actual build dialog to build
+    a document directly to disk.
+    """
 
     def __init__(self, mainGui: GuiMain):
         super().__init__(parent=mainGui)
@@ -98,7 +102,7 @@ class GuiManuscript(QDialog):
         self.buildProgress = QProgressBar()
         self.btnPreview = QPushButton(self.tr("Build Preview"))
         self.btnPreview.clicked.connect(self._generatePreview)
-        self.manPreview = GuiManuscriptPreview(self.mainGui)
+        self.manPreview = _PreviewWidget(self.mainGui)
 
         self.menuPrint = QMenu(self)
         self.aPrintSend = self.menuPrint.addAction(self.tr("Print Preview"))
@@ -166,12 +170,12 @@ class GuiManuscript(QDialog):
         return
 
     def __del__(self):
+        """For debug use only."""
         logger.debug("Delete: GuiManuscript")
         return
 
     def loadContent(self):
-        """Load dialog content from project data.
-        """
+        """Load dialog content from project data."""
         self._builds.loadCollection()
         self._updateBuildsList()
         return
@@ -181,7 +185,9 @@ class GuiManuscript(QDialog):
     ##
 
     def closeEvent(self, event):
-        """Capture the user closing the window so we can save settings.
+        """Capture the user closing the window so we can save GUI
+        settings. We also check that we don't have a build settings
+        diralog open.
         """
         self._saveSettings()
         for obj in self.children():
@@ -198,8 +204,7 @@ class GuiManuscript(QDialog):
 
     @pyqtSlot()
     def _createNewBuild(self):
-        """Open the build settings dialog for a new build.
-        """
+        """Open the build settings dialog for a new build."""
         build = BuildSettings()
         build.setName(self.tr("My Manuscript"))
         self._openSettingsDialog(build)
@@ -207,8 +212,7 @@ class GuiManuscript(QDialog):
 
     @pyqtSlot()
     def _editSelectedBuild(self):
-        """Edit the currently selected build settings entry.
-        """
+        """Edit the currently selected build settings entry."""
         build = self._getSelectedBuild()
         if build is not None:
             self._openSettingsDialog(build)
@@ -216,8 +220,7 @@ class GuiManuscript(QDialog):
 
     @pyqtSlot(BuildSettings)
     def _processNewSettings(self, build: BuildSettings):
-        """Process new build settings from the settings dialog.
-        """
+        """Process new build settings from the settings dialog."""
         self._builds.setBuild(build)
         self._builds.saveCollection()
         self._updateBuildItem(build)
@@ -263,8 +266,7 @@ class GuiManuscript(QDialog):
 
     @pyqtSlot()
     def _doClose(self):
-        """The close button has been clicked.
-        """
+        """Forward the close button to the default close method."""
         self.close()
         return
 
@@ -273,8 +275,7 @@ class GuiManuscript(QDialog):
     ##
 
     def _getSelectedBuild(self) -> BuildSettings | None:
-        """Get the currently selected build.
-        """
+        """Get the currently selected build."""
         bItems = self.buildList.selectedItems()
         if bItems:
             build = self._builds.getBuild(bItems[0].data(Qt.UserRole))
@@ -283,13 +284,11 @@ class GuiManuscript(QDialog):
         return None
 
     def _saveManuscript(self, outFormat: int):
-        """Save the manuscript file or files.
-        """
+        """Save the manuscript file or files."""
         return
 
     def _saveSettings(self):
-        """Save the various user settings.
-        """
+        """Save the user GUI settings."""
         logger.debug("Saving GuiManuscript settings")
 
         winWidth  = CONFIG.rpxInt(self.width())
@@ -309,8 +308,7 @@ class GuiManuscript(QDialog):
         return
 
     def _openSettingsDialog(self, build: BuildSettings):
-        """Open the build settings dialog.
-        """
+        """Open the build settings dialog."""
         dlgSettings = GuiBuildSettings(self, self.mainGui, build)
         dlgSettings.setModal(False)
         dlgSettings.show()
@@ -321,8 +319,7 @@ class GuiManuscript(QDialog):
         return
 
     def _updateBuildsList(self):
-        """Update the list of available builds.
-        """
+        """Update the list of available builds."""
         self.buildList.clear()
         for key, name in self._builds.builds():
             bItem = QListWidgetItem()
@@ -333,8 +330,7 @@ class GuiManuscript(QDialog):
         return
 
     def _updateBuildItem(self, build: BuildSettings):
-        """Update the entry of a specific build item.
-        """
+        """Update the entry of a specific build item."""
         bItem = self._buildMap.get(build.buildID, None)
         if isinstance(bItem, QListWidgetItem):
             bItem.setText(build.name)
@@ -345,7 +341,7 @@ class GuiManuscript(QDialog):
 # END Class GuiManuscript
 
 
-class GuiManuscriptPreview(QTextBrowser):
+class _PreviewWidget(QTextBrowser):
 
     def __init__(self, mainGui: GuiMain):
         super().__init__(parent=mainGui)
@@ -357,8 +353,7 @@ class GuiManuscriptPreview(QTextBrowser):
         return
 
     def setContent(self, data: dict):
-        """
-        """
+        """Set the content of the preview widget."""
         sPos = self.verticalScrollBar().value()
         qApp.setOverrideCursor(QCursor(Qt.WaitCursor))
 
@@ -377,4 +372,4 @@ class GuiManuscriptPreview(QTextBrowser):
 
         return
 
-# END Class GuiManuscriptPreview
+# END Class _PreviewWidget
diff --git a/novelwriter/tools/manussettings.py b/novelwriter/tools/manussettings.py
index c05bda6b..f97df0c5 100644
--- a/novelwriter/tools/manussettings.py
+++ b/novelwriter/tools/manussettings.py
@@ -1,10 +1,9 @@
 """
 novelWriter – GUI Build Settings
 ================================
-GUI classes for editing Manuscript Build Settings
 
 File History:
-Created: 2023-02-13 [2.1b1]
+Created: 2023-02-13 [2.1b1] GuiBuildSettings
 
 This file is a part of novelWriter
 Copyright 2018–2023, Veronica Berglyd Olsen
@@ -34,8 +33,8 @@ from PyQt5.QtGui import (
 from PyQt5.QtCore import QEvent, QSize, Qt, pyqtSignal, pyqtSlot
 from PyQt5.QtWidgets import (
     QAbstractButton, QAbstractItemView, QComboBox, QDialog, QDialogButtonBox,
-    QDoubleSpinBox, QFontDialog, QFrame, QGridLayout, QHBoxLayout, QHeaderView, QLabel,
-    QLineEdit, QMenu, QPlainTextEdit, QPushButton, QSpinBox, QSplitter,
+    QDoubleSpinBox, QFontDialog, QFrame, QGridLayout, QHBoxLayout, QHeaderView,
+    QLabel, QLineEdit, QMenu, QPlainTextEdit, QPushButton, QSpinBox, QSplitter,
     QStackedWidget, QToolButton, QTreeWidget, QTreeWidgetItem, QVBoxLayout,
     QWidget
 )
@@ -56,6 +55,11 @@ logger = logging.getLogger(__name__)
 
 
 class GuiBuildSettings(QDialog):
+    """GUI Tools: Manuscript Build Settings Dialog
+
+    The main tool for configuring manuscript builds. It's a GUI tool for
+    editing JSON build definitions, wrapped as a BuildSettings object.
+    """
 
     OPT_FILTERS  = 1
     OPT_HEADINGS = 2
@@ -112,11 +116,11 @@ class GuiBuildSettings(QDialog):
         # ============
 
         # Create Tabs
-        self.optTabSelect = GuiBuildFilterTab(self, self._build)
-        self.optTabHeadings = GuiBuildHeadingsTab(self, self._build)
-        self.optTabFormat = GuiBuildFormatTab(self, self._build)
-        self.optTabContent = GuiBuildContentTab(self, self._build)
-        self.optTabOutput = GuiBuildOutputTab(self, self._build)
+        self.optTabSelect = _FilterTab(self, self._build)
+        self.optTabHeadings = _HeadingsTab(self, self._build)
+        self.optTabFormat = _FormatTab(self, self._build)
+        self.optTabContent = _ContentTab(self, self._build)
+        self.optTabOutput = _OutputTab(self, self._build)
 
         # Add Tabs
         self.toolStack = QStackedWidget(self)
@@ -164,11 +168,11 @@ class GuiBuildSettings(QDialog):
         return
 
     def __del__(self):
+        """For debug use only."""
         logger.debug("Delete: GuiBuildSettings")
 
     def loadContent(self):
-        """Populate the child widgets.
-        """
+        """Populate the child widgets."""
         self.editBuildName.setText(self._build.name)
         self.optTabSelect.loadContent()
         self.optTabHeadings.loadContent()
@@ -183,8 +187,7 @@ class GuiBuildSettings(QDialog):
 
     @pyqtSlot(int)
     def _stackPageSelected(self, pageId: int):
-        """Process a user request to switch page.
-        """
+        """Process a user request to switch page."""
         if pageId == self.OPT_FILTERS:
             self.toolStack.setCurrentWidget(self.optTabSelect)
         elif pageId == self.OPT_HEADINGS:
@@ -199,8 +202,7 @@ class GuiBuildSettings(QDialog):
 
     @pyqtSlot("QAbstractButton*")
     def _dialogButtonClicked(self, button: QAbstractButton):
-        """Handle button clicks from the dialog button box.
-        """
+        """Handle button clicks from the dialog button box."""
         role = self.dlgButtons.buttonRole(button)
         if role == QDialogButtonBox.ApplyRole:
             self._emitBuildData()
@@ -216,7 +218,8 @@ class GuiBuildSettings(QDialog):
     ##
 
     def closeEvent(self, event: QEvent):
-        """Capture the user closing the window so we can save settings.
+        """Capture the user closing the window so we can save
+        settings.
         """
         logger.debug("Closing: GuiBuildSettings")
         self._askToSaveBuild()
@@ -244,8 +247,7 @@ class GuiBuildSettings(QDialog):
         return
 
     def _saveSettings(self):
-        """Save the various user settings.
-        """
+        """Save the various user settings."""
         logger.debug("Saving GuiBuildSettings settings")
 
         winWidth  = CONFIG.rpxInt(self.width())
@@ -263,8 +265,7 @@ class GuiBuildSettings(QDialog):
         return
 
     def _emitBuildData(self):
-        """Assemble the build data and emit the signal.
-        """
+        """Assemble the build data and emit the signal."""
         self._build.setName(self.editBuildName.text())
         self.optTabHeadings.saveContent()
         self.optTabContent.saveContent()
@@ -277,7 +278,7 @@ class GuiBuildSettings(QDialog):
 # END Class GuiBuildSettings
 
 
-class GuiBuildFilterTab(QWidget):
+class _FilterTab(QWidget):
 
     C_DATA   = 0
     C_NAME   = 0
@@ -398,15 +399,13 @@ class GuiBuildFilterTab(QWidget):
         return
 
     def loadContent(self):
-        """Populate the widgets.
-        """
+        """Populate the widgets."""
         self._populateTree()
         self._populateFilters()
         return
 
     def mainSplitSizes(self) -> tuple[int, int]:
-        """Extract the sizes of the main splitter.
-        """
+        """Extract the sizes of the main splitter."""
         sizes = self.mainSplit.sizes()
         if len(sizes) < 2:
             return 0, 0
@@ -418,8 +417,7 @@ class GuiBuildFilterTab(QWidget):
 
     @pyqtSlot(str, bool)
     def _applyFilterSwitch(self, key: str, state: bool):
-        """A filter switch has been toggled, so update the settings.
-        """
+        """Apply filter switch and update the settings."""
         if key.startswith("doc:"):
             self._build.setValue(key[4:], state)
             self._setTreeItemMode()
@@ -433,8 +431,7 @@ class GuiBuildFilterTab(QWidget):
     ##
 
     def _populateTree(self):
-        """Build the tree of project items.
-        """
+        """Build the tree of project items."""
         logger.debug("Building project tree")
         self._treeMap = {}
         self.optTree.clear()
@@ -490,8 +487,7 @@ class GuiBuildFilterTab(QWidget):
         return
 
     def _populateFilters(self):
-        """Populate the filter options switches.
-        """
+        """Populate the filter options switches."""
         self.filterOpt.clear()
         self.filterOpt.addLabel(self._build.getLabel("filter"))
         self.filterOpt.addItem(
@@ -530,8 +526,7 @@ class GuiBuildFilterTab(QWidget):
         return
 
     def _setSelectedMode(self, mode: int):
-        """Set the mode for the selected items.
-        """
+        """Set the mode for the selected items."""
         for item in self.optTree.selectedItems():
             if not isinstance(item, QTreeWidgetItem):
                 continue
@@ -551,8 +546,7 @@ class GuiBuildFilterTab(QWidget):
         return
 
     def _setTreeItemMode(self):
-        """Update the filtered mode icon on all items.
-        """
+        """Update the filtered mode icon on all items."""
         filtered = self._build.buildItemFilter(self.theProject)
         for tHandle, item in self._treeMap.items():
             allow, mode = filtered.get(tHandle, (False, FilterMode.UNKNOWN))
@@ -566,10 +560,10 @@ class GuiBuildFilterTab(QWidget):
                 item.setIcon(self.C_STATUS, self._statusFlags[self.F_NONE][1])
         return
 
-# END Class GuiBuildFilterTab
+# END Class _FilterTab
 
 
-class GuiBuildHeadingsTab(QWidget):
+class _HeadingsTab(QWidget):
 
     EDIT_TITLE   = 1
     EDIT_CHAPTER = 2
@@ -707,7 +701,7 @@ class GuiBuildHeadingsTab(QWidget):
         self.editTextBox.setFixedHeight(5*iPx)
         self.editTextBox.setEnabled(False)
 
-        self.formSyntax = GuiHeadingSyntax(self.editTextBox.document(), self.mainTheme)
+        self.formSyntax = _HeadingSyntaxHighlighter(self.editTextBox.document(), self.mainTheme)
 
         self.menuInsert = QMenu()
         self.aInsTitle = self.menuInsert.addAction(self.tr("Title"))
@@ -756,8 +750,7 @@ class GuiBuildHeadingsTab(QWidget):
         return
 
     def loadContent(self):
-        """Populate the widgets.
-        """
+        """Populate the widgets."""
         self.fmtTitle.setText(self._build.getStr("headings.fmtTitle"))
         self.fmtChapter.setText(self._build.getStr("headings.fmtChapter"))
         self.fmtUnnumbered.setText(self._build.getStr("headings.fmtUnnumbered"))
@@ -768,8 +761,7 @@ class GuiBuildHeadingsTab(QWidget):
         return
 
     def saveContent(self):
-        """Save choices back into build object.
-        """
+        """Save choices back into build object."""
         self._build.setValue("headings.hideScene", self.swtScene.isChecked())
         self._build.setValue("headings.hideSection", self.swtSection.isChecked())
         return
@@ -779,8 +771,7 @@ class GuiBuildHeadingsTab(QWidget):
     ##
 
     def _insertIntoForm(self, text: str):
-        """Insert formatting text from the dropdown menu.
-        """
+        """Insert formatting text from the dropdown menu."""
         if self._editing > 0:
             cursor = self.editTextBox.textCursor()
             cursor.insertText(text)
@@ -788,8 +779,7 @@ class GuiBuildHeadingsTab(QWidget):
         return
 
     def _editHeading(self, heading: int):
-        """Populate the form with a specific heading format.
-        """
+        """Populate the form with a specific heading format."""
         self._editing = heading
         self.editTextBox.setEnabled(True)
         if heading == self.EDIT_TITLE:
@@ -823,8 +813,7 @@ class GuiBuildHeadingsTab(QWidget):
     ##
 
     def _saveFormat(self):
-        """Save the format from the edit text box.
-        """
+        """Save the format from the edit text box."""
         heading = self._editing
         text = self.editTextBox.toPlainText().replace("\n", "//")
         if heading == self.EDIT_TITLE:
@@ -850,10 +839,10 @@ class GuiBuildHeadingsTab(QWidget):
 
         return
 
-# END Class GuiBuildHeadingsTab
+# END Class _HeadingsTab
 
 
-class GuiHeadingSyntax(QSyntaxHighlighter):
+class _HeadingSyntaxHighlighter(QSyntaxHighlighter):
 
     def __init__(self, document: QTextDocument, mainTheme: GuiTheme):
         super().__init__(document)
@@ -864,8 +853,7 @@ class GuiHeadingSyntax(QSyntaxHighlighter):
         return
 
     def highlightBlock(self, text: str):
-        """Add syntax highlighting to the text block.
-        """
+        """Add syntax highlighting to the text block."""
         for heading in nwHeadFmt.ALL:
             pos = text.find(heading)
             if pos >= 0:
@@ -877,10 +865,10 @@ class GuiHeadingSyntax(QSyntaxHighlighter):
                     self.setFormat(pos + ddots, 1, self._fmtSymbol)
         return
 
-# END Class GuiHeadingSyntax
+# END Class _HeadingSyntaxHighlighter
 
 
-class GuiBuildContentTab(QWidget):
+class _ContentTab(QWidget):
 
     def __init__(self, buildMain: GuiBuildSettings, build: BuildSettings):
         super().__init__(parent=buildMain)
@@ -932,8 +920,7 @@ class GuiBuildContentTab(QWidget):
         return
 
     def loadContent(self):
-        """Populate the widgets.
-        """
+        """Populate the widgets."""
         self.incSynopsis.setChecked(self._build.getBool("text.includeSynopsis"))
         self.incComments.setChecked(self._build.getBool("text.includeComments"))
         self.incKeywords.setChecked(self._build.getBool("text.includeKeywords"))
@@ -942,8 +929,7 @@ class GuiBuildContentTab(QWidget):
         return
 
     def saveContent(self):
-        """Save choices back into build object.
-        """
+        """Save choices back into build object."""
         self._build.setValue("text.includeSynopsis", self.incSynopsis.isChecked())
         self._build.setValue("text.includeComments", self.incComments.isChecked())
         self._build.setValue("text.includeKeywords", self.incKeywords.isChecked())
@@ -951,10 +937,10 @@ class GuiBuildContentTab(QWidget):
         self._build.setValue("text.addNoteHeadings", self.addNoteHead.isChecked())
         return
 
-# END Class GuiBuildContentTab
+# END Class _ContentTab
 
 
-class GuiBuildFormatTab(QWidget):
+class _FormatTab(QWidget):
 
     def __init__(self, buildMain: GuiBuildSettings, build: BuildSettings):
         super().__init__(parent=buildMain)
@@ -1035,8 +1021,7 @@ class GuiBuildFormatTab(QWidget):
         return
 
     def loadContent(self):
-        """Populate the widgets.
-        """
+        """Populate the widgets."""
         langIdx = self.buildLang.findData(self._build.getStr("format.buildLang"))
         if langIdx != -1:
             self.buildLang.setCurrentIndex(langIdx)
@@ -1056,8 +1041,7 @@ class GuiBuildFormatTab(QWidget):
         return
 
     def saveContent(self):
-        """Save choices back into build object.
-        """
+        """Save choices back into build object."""
         self._build.setValue("format.buildLang", str(self.buildLang.currentData()))
         self._build.setValue("format.textFont", self.textFont.text())
         self._build.setValue("format.textSize", self.textSize.value())
@@ -1073,8 +1057,7 @@ class GuiBuildFormatTab(QWidget):
 
     @pyqtSlot()
     def _selectFont(self):
-        """Open the QFontDialog and set a font for the font style.
-        """
+        """Open the QFontDialog and set a font for the font style."""
         currFont = QFont()
         currFont.setFamily(self.textFont.text())
         currFont.setPointSize(self.textSize.value())
@@ -1084,10 +1067,10 @@ class GuiBuildFormatTab(QWidget):
             self.textSize.setValue(theFont.pointSize())
         return
 
-# END Class GuiBuildFormatTab
+# END Class _FormatTab
 
 
-class GuiBuildOutputTab(QWidget):
+class _OutputTab(QWidget):
 
     def __init__(self, buildMain: GuiBuildSettings, build: BuildSettings):
         super().__init__(parent=buildMain)
@@ -1133,17 +1116,15 @@ class GuiBuildOutputTab(QWidget):
         return
 
     def loadContent(self):
-        """Populate the widgets.
-        """
+        """Populate the widgets."""
         self.odtAddColours.setChecked(self._build.getBool("odt.addColours"))
         self.htmlAddStyles.setChecked(self._build.getBool("html.addStyles"))
         return
 
     def saveContent(self):
-        """Save choices back into build object.
-        """
+        """Save choices back into build object."""
         self._build.setValue("odt.addColours", self.odtAddColours.isChecked())
         self._build.setValue("html.addStyles", self.htmlAddStyles.isChecked())
         return
 
-# END Class GuiBuildOutputTab
+# END Class _OutputTab