user32: Make sure that IsWindowVisible returns FALSE for HWND_MESSAGE windows.
diff --git a/server/window.c b/server/window.c
index ed8f042..303a6cf 100644
--- a/server/window.c
+++ b/server/window.c
@@ -604,7 +604,7 @@
 /* check if window and all its ancestors are visible */
 static int is_visible( const struct window *win )
 {
-    while (win && win->parent)
+    while (win)
     {
         if (!(win->style & WS_VISIBLE)) return 0;
         win = win->parent;