Only skip setting swap in windowShow

With the early return, mainUpdate doesn't get called in cases where
other functions expect windowShow to call it, such as when closing
or moving windows.

ui.c

@@ -770,10 +770,11 @@ static void inputUpdate(void) {
 }
 
 static void windowShow(uint num) {
-	windows.user = num;
-	if (windows.show == num) return;
+	if (num != windows.show) {
 		windows.swap = windows.show;
+	}
 	windows.show = num;
+	windows.user = num;
 	mark(windows.ptrs[windows.swap]);
 	unmark(windows.ptrs[windows.show]);
 	mainUpdate();