GTK+ Widgets and Objects

Windows & Dialogs
    GtkWindow
    GtkDialog
    GtkColorSelectionDialog
    GtkFileSelection
    GtkFontSelectionDialog
    GtkInputDialog

Containers
    GtkHBox
    GtkVBox
    GtkTable
    GtkToolbar
    GtkHandleBox
    GtkNotebook
    GtkFrame
    GtkAspectFrame
    GtkFixed
    GtkPacker
    GtkLayout
    GtkScrolledWindow
    GtkViewport
    GtkEventBox
    GtkAlignment
    GtkHButtonBox
    GtkVButtonBox
    GtkHPaned
    GtkVPaned

Labels & Buttons
    GtkLabel
    GtkAccelLabel
    GtkButton
    GtkCheckButton
    GtkToggleButton
    GtkRadioButton

Data Entry Widgets
    GtkEntry
    GtkText
    GtkSpinButton
    GtkOptionMenu
    GtkCombo
    GtkHScale
    GtkVScale

Lists & Trees
    GtkCList
    GtkCTree
    GtkList
    GtkListItem
    GtkTree
    GtkTreeItem

Tooltips
    GtkTooltips
    GtkTipsQuery

Menus & Menu Bars
    GtkMenuBar
    GtkMenu
    GtkMenuItem
    GtkCheckMenuItem
    GtkRadioMenuItem
    GtkTearoffMenuItem

Graphical Widgets
    GtkDrawingArea
    GtkImage
    GtkPixmap
    GtkPreview
    GtkCurve
    GtkGammaCurve

Misc. Widgets
    GtkArrow
    GtkCalendar
    GtkProgressBar
    GtkStatusbar
    GtkHRuler
    GtkVRuler
    GtkHScrollbar
    GtkVScrollbar
    GtkHSeparator
    GtkVSeparator
    GtkColorSelection
    GtkFontSelection

Abstract Base Classes
    GtkWidget
    GtkObject
    GtkContainer
    GtkBin
    GtkBox
    GtkButtonBox
    GtkData
    GtkEditable
    GtkItem
    GtkMenuShell
    GtkMisc
    GtkPaned
    GtkProgress
    GtkRange
    GtkRuler
    GtkScale
    GtkScrollbar
    GtkSeparator

Integrating with other X Applications
    GtkPlug
    GtkSocket

Misc. Objects
    GtkAdjustment
    GtkItemFactory
    GtkInvisible