Dumb Window size Question

[stomfi]

I'm using a runrev runtime on a Linux Live CD.
Depending on the platform, the live CD sets the screen size from the 
capabilities of the video card, using a frame buffer.
This can be any valid size from 1200x1024 to 640x480.

I can easily find out the screen size with the xwininfo shell tool.

I want to know how I can tell my runrev windows and all objects on 
them to scale for these different screen sizes.

I am a real newbie for the under the hood stuff as I use runrev for 
the GUI bits and do all the information processing with the 
wonderful Linux shell tools.