xwayland: Stack windows on top when activating them

Now that we've removed the XYToWindow handler in Xwayland, we actually
have to stack windows properly. This stacks windows on top when
activating them.

Note that for a fully robust Xwayland implementation, we'll need a
complete stack tracker implementation, unfortunately.

Reviewed-by: Daniel Stone <daniels@collabora.com>

xwayland/window-manager.c

@@ -720,6 +720,8 @@ weston_wm_window_activate(struct wl_listener *listener, void *data)
 	}
 
 	if (window) {
+		uint32_t values[1];
+
 		if (window->override_redirect)
 			return;
 
@@ -736,6 +738,10 @@ weston_wm_window_activate(struct wl_listener *listener, void *data)
 
 		xcb_set_input_focus (wm->conn, XCB_INPUT_FOCUS_POINTER_ROOT,
 				     window->id, XCB_TIME_CURRENT_TIME);
+
+		values[0] = XCB_STACK_MODE_ABOVE;
+		xcb_configure_window (wm->conn, window->frame_id,
+				      XCB_CONFIG_WINDOW_STACK_MODE, values);
 	} else {
 		xcb_set_input_focus (wm->conn,
 				     XCB_INPUT_FOCUS_POINTER_ROOT,