The destroy_event signal is emitted when a Window is destroyed.
You rarely get this signal, because most widgets disconnect themselves from their window before they destroy it, so no widget owns the window at destroy time.
To receive this signal, the Window associated to the widget needs to enable the STRUCTURE_MASK mask. GDK will enable this mask automatically for all new windows.
the event which triggered this signal
true to stop other handlers from being invoked for the event. false to propagate the event further.