For most purposes this function is deprecated in favor of
g_object_set_data(). However, for historical reasons GTK+ stores
the gtk.Widget that owns a gdk.Window as user data on the
gdk.Window So, custom widget implementations should use
this function for that. If GTK+ receives an event for a gdk.Window,
and the user data for the window is non-NULL, GTK+ will assume the
user data is a gtk.Widget, and forward the event to that widget.
For most purposes this function is deprecated in favor of g_object_set_data(). However, for historical reasons GTK+ stores the gtk.Widget that owns a gdk.Window as user data on the gdk.Window So, custom widget implementations should use this function for that. If GTK+ receives an event for a gdk.Window, and the user data for the window is non-NULL, GTK+ will assume the user data is a gtk.Widget, and forward the event to that widget.