Tried all possible ways to give visibility to tray icons in Ubuntu 12.04 but no luck :(
- Dconf-editor -> Navigate to Desktop -> Unity -> Panel -> change the value of systray-whitelist to "all"
- gsettings set com.canonical.Unity.Panel systray-whitelist "['all']"
- Set values of above to include pidgin, davmail, etc.
Please note that only some tray icons are invisible. I still cant see pidgin, davmail, guake tray icons. I am on Ubuntu 12.04 Gnome classic mode (gnome-session-fallback).