Thanks for your comments.  They lead to lots to think about and try.
>
> I looked up "sprite sheets" and they seem to be graphics that  
> include lots of little tiled figures used in video games.
> How does a browser know to split them up into separate images that  
> pages can then call out individually?
>
> Ask Google ;)
>
>  http://www.websiteoptimization.com/speed/tweak/css-sprites/
>
You should have said "CSS sprites" rather than "sprite sheets".

The techniques cited look much harder to use than CloseKeepAlive, plus
the comments at the end of the article say they don't work on MSIE, or
(per another comment) on MSIE < 8.

Looks like a technique that needs a new CPAN module to help mere mortals
use it.  Something to keep you out of mischief?

Anyway I guess I'll muddle through with submitting CloseKeepAlive to  
CPAN.
(This list has been quite helpful as to how to do that.)  Obviously  
it's not for
you, but maybe it can be useful to people less technologically advanced
than you.  Or as an example of how to use IPC::MMA.

Thanks again,
cmac