Gtk_Object
  +-- Gtk_Data
  |     +-- Gtk_Tooltips
  |     \__ Gtk_Adjustment
  \__ Gtk_Widget  @i{(Visual widgets)}
        +-- Gtk_Calendar
        +-- Gtk_Container  @i{(Widgets that have children)}
        |     +-- Gtk_Bin  @i{(Widgets that have a single child)}
        |     |     +-- Gtk_Alignment
        |     |     +-- Gtk_Button @i{(Widgets that you can click)}
        |     |     |     +-- Gtk_Option_Menu
        |     |     |     +-- Gtk_Toggle_Button
        |     |     |     |     \__ Gtk_Check_Button
        |     |     |     |           \__ Gtk_Radio_Button
        |     |     +-- Gtk_Event_Box
        |     |     +-- Gtk_Frame
        |     |     |     \__ Gtk_Aspect_Frame
        |     |     +-- Gtk_Handle_Box
        |     |     +-- Gtk_Invisible
        |     |     +-- Gtk_Item
        |     |     |     +-- Gtk_List_Item
        |     |     |     +-- Gtk_Menu_Item
        |     |     |     |     +-- Gtk_Check_Menu_Item
        |     |     |     |     |     \__ Gtk_Radio_Menu_Item
        |     |     |     |     \__ Gtk_Tearoff_Menu_Item
        |     |     |     \__ Gtk_Tree_Item
        |     |     +-- Gtk_Viewport
        |     |     \__ Gtk_Window  @i{(Have an independent window)}
        |     |           +-- Gtk_Color_Selection_Dialog
        |     |           +-- Gtk_Dialog
        |     |           |     \__ Gtk_Input_Dialog
        |     |           +-- Gtk_File_Selection
        |     |           +-- Gtk_Font_Selection_Dialog
        |     |           \__ Gtk_Plug
        |     +-- Gtk_Box  @i{(Widgets that have one or more children)}
        |     |     +-- Gtk_Button_Box
        |     |     |     +-- Gtk_Vbutton_Box
        |     |     |     \__ Gtk_Hbutton_Box
        |     |     +-- Gtk_Color_Selection
        |     |     +-- Gtk_Combo
        |     |     +-- Gtk_Gamma_Curve
        |     |     \__ Gtk_Status_Bar
        |     +-- Gtk_Clist
        |     |     \__ Gtk_Ctree
        |     +-- Gtk_Fixed
        |     +-- Gtk_Layout
        |     +-- Gtk_List
        |     +-- Gtk_Menu_Shell
        |     |     +-- Gtk_Menu
        |     |     \__ Gtk_Menu_Bar
        |     +-- Gtk_Notebook
        |     |     \__ Gtk_Font_Selection
        |     +-- Gtk_Packer
        |     +-- Gtk_Paned
        |     +-- Gtk_Scrolled_Window
        |     +-- Gtk_Socket
        |     +-- Gtk_Toolbar
        |     +-- Gtk_Table
        |     \__ Gtk_Tree
        +-- Gtk_Drawing_Area
        |     \__ Gtk_Curve
        +-- Gtk_Editable
        |     +-- Gtk_Entry
        |     |     \__ Gtk_Spin_Button
        |     \__ Gtk_Text
        +-- Gtk_Misc
        |     +-- Gtk_Arrow
        |     +-- Gtk_Image
        |     +-- Gtk_Label
        |     |     +-- Gtk_Accel_Label
        |     |     \__ Gtk_Tips_Query
        |     \__ Gtk_Pixmap
        +-- Gtk_Preview
        +-- Gtk_Progress
        |     \__ Gtk_Progress_Bar
        +-- Gtk_Range
        |     +-- Gtk_Scale
        |     \__ Gtk_Scrollbar
        +-- Gtk_Ruler
        \__ Gtk_Separator