EF notifier is a Tk library that I have just made available [L1 ]. Maybe the name was badly chosen... notifier is a very raw package, you might want to use osd instead. osd will give you the ability to specify the content of the notification.
floatingbbar is another library written on top of the notifier. It provides button bars that pop up from one side of the screen when the mouse hoovers over them.
Where: http://www.sics.se/~emmanuel/?Code:notifier
Description: The notifier library implements a new Tcl/Tk widget that presents itself
as an (animated) notifier that pops up from one of the side of the screen
in a direction that can be chosen. The notifier is a new toplevel and it
is up to the caller to fill it in with content.
Updated: 05/2006
Contact: Emmanuel Frecon, see web site