Comment 6 for bug 290552

+1 for Alex. Before trying to change the default tray icon behavior, we must try not to lose the minimize-to-tray feature *by default*. That could be considered as a regression. Also, changing the default setting isn't obvious for all users.

"Additionally, the HIG states that if it does anything other than opening a window, it should be an applet, rather than showing up as if it was a notification icon."

Pidgin (formerly Gaim) had an applet some time ago, but was replaced by the minimize-to-tray feature, AFAIK.