gtk widgets structure

+-- gobject.GObject
  +-- gtk.gdk.Drawable
    +-- gtk.gdk.Window      

+-- gobject.GObject
  +-- gtk.Object
    +-- gtk.Widget
      +-- gtk.Container
        +-- gtk.Bin
          +-- gtk.Button      

GObject
   +----GtkObject
         +----GtkWidget
               +----GtkContainer
                     +----GtkBin
                           +----GtkButton
                                 +----GtkToggleButton
                                 +----GtkColorButton
                                 +----GtkFontButton
                                 +----GtkOptionMenu      

GObject
   +----GInitiallyUnowned
         +----GtkObject
               +----GtkWidget
                     +----GtkContainer
                           +----GtkBin
                                 +----GtkWindow
                                       +----GtkDialog
                                             +----GtkFileChooserDialog