public Object tooltip(Coord c, boolean again) {
		if (tooltip != null) {
			prevtt = null;
			return (tooltip);
		}
		for (Widget wdg = lchild; wdg != null; wdg = wdg.prev) {
			if (!wdg.visible)
				continue;
			Coord cc = xlate(wdg.c, true);
			if (c.isect(cc, wdg.sz)) {
				Object ret = wdg.tooltip(c.add(cc.inv()), again
						&& (wdg == prevtt));
				if (ret != null) {
					prevtt = wdg;
					return (ret);
				}
			}
		}
		prevtt = null;
		return (null);
	}