winedos/int10 clearscreen fix

[Jukka Heinonen]

> I've had issues with a console program not clearing the screen when it's
> supposed to. I've traced the problem down to dlls/winedos/int10.c function
> DOSVM_Int10Handler() with and AH reg of 0x0b.

Are you sure you found the right place to fix? According to
interrupt documentation, 0x0b subfunction 0x00 is supposed to only
set background color. It is possible that the subfunction also clears 
screen but I would like you to make sure that this is the real place 
missing clear screen.

One place that is certain to have missing clear screen is entering 
text mode. Right now VGA emulation does not do this; VGA_SetAlphaMode
should have a boolean flag that tells whether clear screen is desired or
not and this flag should be set according to VGA mode bit 7 (or some
VESA mode flag). I suspect that this is what is really causing the bug 
you have observed. Perhaps you should check whether this is the case? 

I will try to make a patch that fixes clear screen bug when
entering text mode but it might take a few days (and it might be
that this is not an issue here, anyway).

-- 
Jukka Heinonen <http://www.iki.fi/jhei/>