Comment 4 for bug 311908

As best as I can tell, there is no way to implement this is a window-manager generic fashion, which means that it isn't going to be implemented at all at this time (as AllTray does not do WM or DE-specific kludges, and hasn't the support for it).

If a way to do this becomes possible, a new bug requesting this feature can be filed, preferably with pointers to the information that makes the implementation possible.