How to change the X view port!

[Carlos Eduardo Rodrigues Diogenes]

Hi,

I don't know much about the internals of the X Window System, but I 
think that when something goes to the screen it's first clipped and then 
drawed.

I will first explain the context, then what I have doubt if could be done.

I'm trying to help the GNOME Accessibility Project, studying the 
gnome-mag and how to improve it and we have a problem to lost space in 
desktopo when we magnifie part of it, for example, the screen is splited 
vertically and in one half we have the normal screen and in the other 
half we have a parte of the normal screen magnified. So we have a half 
of the normal screen under the magnifier.

So, what I want to know is if we have some way in X or if it can be 
easely implemented to chage the part of the screen that is clipped and 
send to display, so when the user move the pointer in direction of the 
magnified screen, the pointer don't go in the magnified screen, but the 
half screen start to appear? What I think that must be done is change 
the origin clipping coordinate to be clipped foward.

Thanks,
Carlos.