# pop-up menus.# use choicebuttons instead - it's difficult to get these right.Popup: module {	PATH: con "/dis/lib/popup.dis";	init: fn();#	mkbutton: fn(win: ref Tk->Toplevel, w: string, a: array of string, n: int): chan of string;#	changebutton: fn(win: ref Tk->Toplevel, w: string, a: array of string, n: int);#	event: fn(win: ref Tk->Toplevel, e: string, a: array of string): int;#	add: fn(a: array of string, s: string): (array of string, int);	post: fn(win: ref Tk->Toplevel, p: Draw->Point, a: array of string, n: int): chan of int;};