FVWM: Resizing any window to a known geometry

[msibley]

Howdy, 

I'd like to do something like the following: 

SetEnv CAPGEOM '800x600+10+10'
Key F6 A A ThisWindow (!Iconic) Move $[CAPGEOM]

The purpose is to stack various windows at exactly the same resolution
for consistent screen capturing. 

What is the best way to move a window to a known static geometry? Is
there a command that will move/resize a window based on a formatted X11
geometry string? 

Thanks in advance!