video dust

[Mikus Grinbergs]

Installed the SugarLabs xoimages/soas3.img on my XO.  I'm a 
'Terminal session' user.  When I leave this XO sit unattended for a 
while, the screen content gets replaced by "dust" - similar to the 
video corruption that eventually shows up in the text console 
(ctl-alt-F2) of an OLPC build (except that with the OLPC build the 
screen background is dark, but here the screen background is lit). 
When I press a key the correct Terminal screen content gets shown.

mikus