I've upgraded to Raring a couple of days ago, and noticed that certain indicators are not appearing in my Unity panel, while all other do.
Essentially I'm referring to: pyAlienFX (from http://code.google.com/p/pyalienfx/), Thunderbird (with Firetray extension, https://github.com/foudfou/FireTray.git) and pidgin.
Obviously they all did work with previous 12.10.
Here's my solution:
How to re-enable the systray whitelist in Ubuntu 13.04 (Raring Ringtail)
If you use such an application and want the systray whitelist back in Ubuntu 13.04, you can use a PPA that comes with Unity patched to re-enable the systray whitelist. To do this, open a terminal and run the following commands:
sudo add-apt-repository ppa:timekiller/unity-systrayfix
sudo apt-get update
sudo apt-get upgrade
Then, restart Unity by pressing ALT + F2 and entering "unity" or by logging out. Then open Dconf Editor, navigate to com > canonical > unity > panel and the "systray-whitelist" should be displayed there so you can enable some apps to be able to use the systray.
After adding an application to the systray whitelist, remember to restart Unity or else it won't work.
source: http://www.webupd8.org/2013/05/how-to-get-systray-whitelist-back-in.html
