Is it possible to draw on a non-desktop display surface in Windows or linux?

First, let me say that I understand that this isn't really a Qt-specific question, but I thought it might be a good starting point to ask here to at least maybe get a pointer to a more applicable forum that might have an answer. So...

I am currently writing an application in Qt / DX9 for Windows that utilizes multiple monitors. One of the monitor outputs actually drives a special projection unit that displays patterns controlled by the program that have nothing to do with the user UI. This display area / "monitor" should never be part of the desktop. The problem with Windows is that there is no way to do this I know of - I verified this with someone I used to work with at MS that does most of their video rendering architecture.

I'm wondering if linux is somehow better about this - do you know if there is a way to have an extra "monitor" area you can draw on that is not part of the main desktop? That is, your mouse can't go over there, and no other application windows or output will go there ( or at least not unless done explicitly)?

Thanks,

Colby

X supports multi desktops and multi monitors for quite a long time now.
Usually you DO want to have your mouse and keyboard on all screens, so I think by default X will allow mouse and keyboard on all screens.
BUT - you can control which input devices (i.e mouse and keyboard) will work on which screen by manipulating the correct section in xorg.conf.
You should read about setting multiple displays with Xinerama, and about X.org.
Some time ago I had to deal with multiple displays, and while searching on google I stumbled on an HOWTO that explains how to have multiple X sessions for multiple users on one machine, and there they have to add a mouse and keyboard per session, so that could be a good place for you to start... if I find it again, I'll post it.
But look for 'Xinerama multiple screens' on google...

Thanks for the tip. Reading a little about multi mon in X it sounds like there are few possibilities that might work. Hopfully I can do other some things in X that I am able to do in Windows with DX9 such as create perfectly VBI frame synchonized image frames which update at the projector refresh rate... I imagine this is possible at some level since MythTV must be able to do this, although it might all be timed in the video card hardware.