This behavior is also applicable for win 2K SP4.
Here is a partial solution for Win 2K or XP - install an app called rtvreco. This app has an action that will put any application window in system tray but it will have no tray icon just a blank square (a little disturbing). The builtin restore window on detecting activity does not always work - YMMV. To restore app window you need to shut rtvreco app.
I wish icon corral were ported to Win 5.x OS too it did exactly what I wanted and still need. I miss it too :-(
I hope the suggestion is of use for those looking for a work around.
