[AD] dga, depth and doublescan...

[Emmanuel Anne <emanne@xxxxxxxxxx>]

Apparently the DGA2 driver does not support depth changing when in a
doublescan mode.

Example : take exmem.c. Just after install_keyboard put these lines :
   set_color_depth(16);
   set_gfx_mode(GFX_XDGA2, 320, 240, 0, 0);
And run it from a normal XFree server in 16bpp mode.
320x240 is available in doublescan...
Then it works.

Then simply change the depth to 8 in the first line :
you get a very bad screen when running exmem...

Someone reported the same kind of problem with the direct X driver in
windows : changing the color depth was also destroying the screen.

Too bad ! These doublescan modes were very convinient for arcade
modes!!!

I use XFree-4.0.2 with an NVidia geforce 2.