The ::visibility-notify-event will be emitted when the @widget's window is obscured or unobscured.
To receive this signal the #GdkWindow associated to the widget needs to enable the #GDK_VISIBILITY_NOTIFY_MASK mask.
Deprecated: 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.
See Implementation
The ::visibility-notify-event will be emitted when the @widget's window is obscured or unobscured.
To receive this signal the #GdkWindow associated to the widget needs to enable the #GDK_VISIBILITY_NOTIFY_MASK mask.