Yes, that's it! Hot key #1 captures the entire window using Corel Capture. Hot key #2 triggers a Perl subroutine that recursively traverses the widget hierarchy, starting from the toplevel, and writes each widget's geometry to a file. Then, with another script, I can import the captured image as a Tk::Photo and snip pieces out of it based on the geometry file. As a bonus, this part is being done without potentially disturbing a running program. Hmmm ... a nicely interactive app could be made from this, depending on the effort put into it...

Thanks!