- GtkBin — A container with just one child
- GtkBox
- GtkButtonBox
- GtkContainer
- GtkItem
- GtkMenuShell
- GtkMisc
- GtkObject
- GtkPaned
- GtkRange
- GtkScale
- GtkScrollbar
- GtkSeparator
- GtkWidget — Base class for all widgets
- GtkIMContext — Base class for input method contexts