gtk.gdk.Window

gtk.gdk.Window is a rectangular region on the screen. It's a low-level object, used to implement high-level objects such as gtk.Widget and gtk.Window. Agtk.Window is a toplevel window, the object a user might think of as a "window" with a titlebar and so on. A gtk.Window may contain several gtk.gdk.Windowobjects since most widgets use a gtk.gdk.Window.

A gtk.gdk.Window object interacts with the native window system for input and events. Some gtk.Widget objects do not have an associated gtk.gdk.Window and therefore cannot receive events. To receive events on behalf of these "windowless" widgets a gtk.EventBox must be used.

http://www.pygtk.org/pygtk2reference/class-gdkwindow.html

Widgets Without Windows

The following widgets do not have an associated gtk.gdk.window. If you want to capture events, you'll have to use the EventBox. See the section on the EventBox widget.

  gtk.Alignment  gtk.Arrow  gtk.Bin  gtk.Box  gtk.Button  gtk.CheckButton  gtk.Fixed  gtk.Image  gtk.Label  gtk.MenuItem  gtk.Notebook  gtk.Paned  gtk.RadioButton  gtk.Range  gtk.ScrolledWindow  gtk.Separator  gtk.Table  gtk.Toolbar  gtk.AspectFrame  gtk.Frame  gtk.VBox  gtk.HBox  gtk.VSeparator  gtk.HSeparator

http://www.pygtk.org/pygtk2tutorial/sec-WidgetsWithoutWindows.html