applied Connors and Valentins patch to improve the unmapnotify handling of broken clients

dwm.c

@@ -1761,9 +1761,13 @@ unmapnotify(XEvent *e) {
 	Client *c;
 	XUnmapEvent *ev = &e->xunmap;
 
-	if((c = wintoclient(ev->window)))
+	if((c = wintoclient(ev->window))) {
+		if(ev->send_event)
+			setclientstate(c, WithdrawnState);
+		else
 			unmanage(c, False);
 	}
+}
 
 void
 updatebars(void) {