gtk-widget-register-window (widget window)

widget -- a gtk-widget object
window -- a gdk-window object

Registers a GDK window with the widget and sets it up so that the widget recieves events for it. Call the gtk-widget-unregister-window function when destroying the GDK window.

Before 3.8 you needed to call the gdk-window-user-data function directly to set this up. This is now deprecated and you should use the gtk-widget-register-window function instead. Old code will keep working as is, although some new features like transparency might not work perfectly.