win32u: Don't force refresh the display cache on thread desktop change.

dlls/win32u/winstation.c

@@ -264,7 +264,7 @@ BOOL WINAPI NtUserSetThreadDesktop( HDESK handle )
         thread_info->client_info.top_window = 0;
         thread_info->client_info.msg_window = 0;
         if (key_state_info) key_state_info->time = 0;
-        if (was_virtual_desktop != is_virtual_desktop()) update_display_cache( TRUE );
+        if (was_virtual_desktop != is_virtual_desktop()) update_display_cache( FALSE );
     }
     return ret;
 }