Comment 16 for bug 123463

Some information:
1) Reproduce:
It's easier to reproduce it if you keep following software running all together:
    ■　WM setting: Window gets focus while mouse pointer moves over.
    ■　terminal (xfce4-terminal or gnome-terminal )
    ■　firefox
    ■　gthumb (with a picture file opened )
    ■　gimp ( with a picture file opened )
    ■　thunar
    then keep switching between those windows, and do some operations you like, such as: move window, resize window, etc.

2) Emergency solution:
   Once you find any window does not responding, stop any operation IMMEDIATELY. (if you keep doing some operations, e.g. click in other window, try to switch to other workspace, etc. the system will freeze completely, that means you have no choice except shutting down)
   Then press CTRL-ALT-BKSPC , this can restart X, and you can login again.