matrox g400 with compiz on linux

[measwel]

Dear friends,

I am trying to run compiz on a matrox g400 in linux 8.04 lts. When I disable checks, compiz does run, but the max resolution is then 1024. My monitor is 1280 horizontal. When I run a script that checks for compiz compatibility, I see the warning that the matrox supports only 1024 texture size, while compiz needs more. Then there is the suggestion to disable dual heads.

My question is:

1) How can I disable dual heads on the matrox g400 under linux? I tried using matroxset, but I get the errror: Cannot open dev/fb1 no such file ...
2) Will this increase maximum texture size beyond 1024 ?