Intercepting X11 events

[Da Rock]

I'm not 100% sure where else to ask this. I have an annoying window that 
disappears when I click close (ha ha, yes I know it will usually do 
that, but this one doesn't go away) but it is unable to cooperate with 
the system tray so it simply becomes "invisible", and hangs about in the 
background.

In my investigationings I had a brainwave that since I cannot change the 
program (not without enormous effort) in the short term, maybe I can 
find a way to terminate the program and manage it externally with a script.

So I'm looking to find a wrapper, or a script that can intercept the 
close event and kill the process (can't find a better way to handle it). 
Any ideas?

The DE is lightweight (Icewm, LXDE, similar) so the tray is either non 
existent or incompatible; the app itself is (#%$&!) java. Yep, thats 
right - it only speaks Gnome/KDE...

Cheers


Afterword: And yes, it took me that long to figure out the Java systray 
problem and the lack of a solution in my googling.