cross-platform c++ classes?

[Carl Parrish]

>Actually, there are a lot of reasons for it, primarily because of drawing
>and rendering custom graphics, etc. - the documentation for GSD speaks in
>two ways, one in terms of X and another in terms of Windows. By having a
>platform-specific subset I would be able to implement those
>platform-specific aspects separately.
>
But do you need these aspects? I guess now I'm asking more in a general 
way than for your actual implementation. Why would you use windows or X 
specific code when you are going though all the trouble to make is XP? 
Why not use V or QT or XPFE???? You know to feed the dream of write once 
run anywhere. Yeah I know it doesn't really happen in real life but 
wouldn't your time be better servered helping to make the dream come 
true then writing platform-specific code??