[SDL] Hardware cursor behaviour under DirectX

[Sam Lantinga]

> This showed up on #sdl today:

> Under win32, with SDL_FULLSCREEN & SDL_DOUBLEBUFFER, the hardware
> cursor is not visible.

Yep.  It should be listed in the BUGS file.  Ahh, it's not, I'll add it.

Basically, it's very difficult to properly implement a mouse cursor when
the application is writing directly to the video memory and the underlying
API doesn't have the equivalent of a freely aligned overlay sprite.

BTW, you shouldn't rely on the hardware mouse cursor for GL applications
anyway.  It doesn't work on at least one hardware configuration (Voodoo2)

See ya,
	-Sam Lantinga, Lead Programmer, Loki Entertainment Software