If I were doing this, I would use a microsoft development kit make an app to sit in the tray and monitor. When conditions were right, call on your perl TK app to create the 'tray' slideout/popup.

Simply create a main window the size and position and define the activities you want it to have. To make it look like a 'popup/slideout' (drawn without window border/controls) call overrideredirect(0) on your window. Like so:

$mw->overrrideredirect(0)
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Good luck