gtk-sharp 2.10.0.0 Gtk# is thread aware, but not thread safe; See the Gtk# Thread Programming for details. Event sender. Event arguments. Event handler. The event utilizes this delegate: Event data is passed via the parameter. To attach a to an event, add the OutputHandler instance to the event. The methods referenced by the OutputHandler instance are invoked whenever the event is raised, until the OutputHandler is removed from the event. System.Delegate System.Void