Gtk.Widget::selection-clear-event

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

The ::selection-clear-event signal will be emitted when the the @widget's window has lost ownership of a selection.

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