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.