General things, initialization
Drawing and other Low-Level Operations
cairo integration
Windows
Display widgets,
Buttons and toggles
Numeric/text data entry
Multiline text editor
Tree and list widget
Menus, combo box, toolbar
Action-based menus and toolbars
Selectors (file/font/color)
Special-purpose features
File chooser
Layout containers
Ornaments
Printing
Recent
Scrolling
Miscellaneous
Abstract base classes
Cross-process embedding
Non-widgets
Pango text layout modules