gboolean visibility_notify_event ( GtkWidget* self, GdkEventVisibility event, gpointer user_data )
The ::visibility-notify-event will be emitted when the
window is obscured or unobscured.
To receive this signal the
GdkWindow associated to the widget needs
to enable the #GDK_VISIBILITY_NOTIFY_MASK mask.
|Default handler:|| |
The default handler is called after the handlers added via
Modern composited windowing systems with pervasive transparency make it impossible to track the visibility of a window reliably, so this signal can not be guaranteed to provide useful information.