xrandr & mouse in invisible areas

[Gabriel Landais]

Hi,
 I've just set up my brand new Lenovo X300 and I am able to extend my
desktop to an external display using xrandr.
 Main LCD panel uses 1440x900 and external monitor 1680x1050, so I set
up Virtual to 3120 1050.
 But when I use for instance "randr --output VGA --auto --right-of
LVDS", an area under my laptop screen is not displayed. It's ok until
my mouse actually can go there. And as I use a task switcher at the
bottom of this screen, my mouse disappear each time I try to switch
application (I've always been bad in FPS too...).
 Is there a way to prevent the mouse to go outside visible areas until
"GEM" is ready please?
 Regards
Gabriel