/window superclass
 /close {
	% --
	mapped {
		@icon null eq {
			/icon newobject /@icon exch promote @icon
			addslave
		} if
		/map @icon send
		unmap
	} if
} def

/owner_close {
	% --
	@icon null ne {
		/unmap @icon send
	} if
	unmap
} def