Intel 945GM & Dual Head Xinerama (display to big)

Hey Folks,

I’m having a huge problem with my Intel 945 graphic.
I have two monitors:
At first, the laptop builtin-LCD (Acer Aspire 56S Laptop) with 1280x800 pixels at 60Hz.
My second screen is a IISonic-TFT-LCD which I want to use with 1280x1024 pixels at 70Hz.
The GPU is a Intel 945GM Chipset, uses “intel” driver.

I plug the second screen into my laptops vga bus and start the sax2 screen configuration, activating dual head modus and using xinerama multihead. When I then set the screen configuration for my external screen and try to test, the second screen works fine but on my main screen (the laptop screen which should run at 1280x800 pixels) the screensize isn’t set properly.

It looks like the physical screen ends 3 centimeters before the virtual screen ends, so the gnome dock is 3 centimeters underneath the bottom of my screen, which only lets my guess where it actually is.

Of course I could just use the external screen as mainscreen but it really sucks to have my laptop main screen in wrong size which made the actual desktop too huge for it. I guess the setting for the external screen (1280x1024) does also affect the setting for the laptop screen, which just could display 1280x800 pixels, that could explain why the desktop is at the bottom 200 pixels longer than it should be.

Does someone else in here have this problem or is there any hint for me fixing this? I really need the dual screen function to get my work done.