This one is deprecated, but should work much better than any other system tray icon backend we currently have, both in term of supported features and reliability. It justs needs some testing to see where we can enable it now.
With some limitations and some awful hacks, since appindicators can not differentiate left click, right click and middle click. It's already a massive pain to just get a signal when the menu is shown, without actually knowing what opened it.
I love ubuntu.
