>i have a question. Will the GBA display controler display the change
>of HOFS of a background layer while he is already in HWRITE? For
>example, the first 40 y values of a certain scanline will be displayed
>with a HOFS value of 0, the next 200 y with a value of 1? Or is it not
>possible to change the scanline while he is in HWRITE? I have tryed it
>on VisualBoyAdvance, but it doesn't work. So there is possible that
>the emulator does not work correctly, my code is wrong or that the
>display controler don't display such a change.

I haven't tested it, but I would assume it's possible. The emulator is
probably using a line-based renderer instead of a (slow) pixel-based one,
so you won't be able to see the effect.