Here is a workaround, I don't know if it is elegant :
In Compiz Composing Setting Manager ( CCSM) , I disabled the Unity plugin ( on the classique Desktop Session) and all was clear.
Here is a workaround, I don't know if it is elegant :
In Compiz Composing Setting Manager ( CCSM) , I disabled the Unity plugin ( on the classique Desktop Session) and all was clear.