Gtk.Widget::unmap-event

function callback(widget, event:Gdk.EventAny, ):Boolean;

The ::unmap-event signal will be emitted when the @widget's window is unmapped. A window is unmapped when it becomes invisible on the screen.

To receive this signal, the Gdk.Window associated to the widget needs to enable the #GDK_STRUCTURE_MASK mask. GDK will enable this mask automatically for all new windows.

widget: instance of Gtk.Widget that is emitting the signal
event: the Gdk.EventAny which triggered this signal
Returns: true to stop other handlers from being invoked for the event. false to propagate the event further.