winex11: Avoid useless updates of the desktop window Z-order.

dlls/winex11.drv/winpos.c

@@ -68,7 +68,7 @@ void X11DRV_Expose( HWND hwnd, XEvent *xev )
     XExposeEvent *event = &xev->xexpose;
     RECT rect;
     struct x11drv_win_data *data;
-    int flags = RDW_INVALIDATE | RDW_ERASE | RDW_ALLCHILDREN;
+    int flags = RDW_INVALIDATE | RDW_ERASE;
 
     TRACE( "win %p (%lx) %d,%d %dx%d\n",
            hwnd, event->window, event->x, event->y, event->width, event->height );
@@ -89,9 +89,8 @@ void X11DRV_Expose( HWND hwnd, XEvent *xev )
     rect.right  = rect.left + event->width;
     rect.bottom = rect.top + event->height;
 
-    if (event->window == root_window)
-        OffsetRect( &rect, virtual_screen_rect.left, virtual_screen_rect.top );
-
+    if (event->window != root_window)
+    {
         SERVER_START_REQ( update_window_zorder )
         {
             req->window      = hwnd;
@@ -105,6 +104,9 @@ void X11DRV_Expose( HWND hwnd, XEvent *xev )
 
         /* make position relative to client area instead of parent */
         OffsetRect( &rect, -data->client_rect.left, -data->client_rect.top );
+        flags |= RDW_ALLCHILDREN;
+    }
+
     RedrawWindow( hwnd, &rect, 0, flags );
 }