Generated when the window visibility status has changed.
TRUE if the event was sent explicitly.
the new visibility state (GDK_VISIBILITY_FULLY_OBSCURED, GDK_VISIBILITY_PARTIAL or GDK_VISIBILITY_UNOBSCURED).
the type of the event (GDK_VISIBILITY_NOTIFY).
the window which received the event.
Deprecated: Modern composited windowing systems with pervasive transparency make it impossible to track the visibility of a window reliably, so this event can not be guaranteed to provide useful information.