I have a ATI R300 card on my T43. When I am setting compiz fusion with mesa 7.6 and the radeon driver that comes with Ubunt9.10 on a dual monitor with totally 3080*1050 (1400*1050+1680*1050) virtual resolution. There will be a warning that the max texture size is 2048. If I ignore the check, the compiz will work only on an area of 2048*1050, and the rest part of the screen is an ugly tearing stripe. I have seen some online work-arounds talking about using a vertical combination, but my vertical combination is 2100 which also exceeds the limit.
Now if I understand correctly about how hardware works, each pix is mapped to a memory block on the video card (to store what color it should show). Therefore due to the fact that 2048*2048 > 3080*1050, the limitation is not really a hardware limitation, instead it is a problem with the driver. And it seems the solution should not be too complicated, instead of using a two dimensional array (which is easy but waste space), one extra function is needed to convert it to an single array and back.
Correct me if I am wrong. If I am correct, is there a chance anyone could fix the problem?