How do I enable the pidgin system tray icon?

I want to enable the System tray icon for Pidgin in Ubuntu 11.10 (with Unity), but I don't see it.

I have to start it again and again from the launcher panel or from the dash.

Is there a workaround to show the system tray icon in Unity? I think it's the same behavior for Skype and some other applications also.

For 12.10 and older:

execute:

gsettings set com.canonical.Unity.Panel systray-whitelist "['all']"

(from http://www.webupd8.org/2011/10/things-to-tweak-after-installing-ubuntu.html)

and remember to set the system tray to "always" in pidgin preferences.

If the change doesn't take effect immediately, run unity --replace

For 13.04:

The migration of Pidgin to the new libmessaging-menu API, which caused this issue, is now done for Pidgin, but still under testing. Also, only a Ubuntu 13.04 package is provided so far, but since it does not introduce any dependencies on other stuff from 13.04, I was able to just install it from the PPA of the programmer who fixed it. According to his instructions, this is what fixed it for me:

sudo add-apt-repository ppa:jconti/gnome3
sudo apt-get update
sudo apt-get install pidgin-libnotify

You should now have pidgin-libnotify version 0.14-9ubuntu1. In addition, you have to add the following line to /usr/share/applications/pidgin.desktop:

 X-MessagingMenu-UsesChatSection=true

Then restart Pidgin, it should now get an entry in the message indicator menu of the panel again, so that when closing its window, it stays running.

Update

It is NOT necessary (any more) to install this repository as of May 23. Probably the updates have been officially included by now.

Just make sure the libnotify plugin is active! With Ubuntu 12.10 (and previous) and the whitelist for system tray icons you/the user may have deactivated the libnotify plugin on purpose.

In 11.10 Unity has hidden the system tray access to pidgin under the messaging icon that looks like an envelope. If you click it, there should be an entry for Pidgin. Not exactly what you're looking for, but at least it's accessible somehow via the system tray.

manually:

1. run dconf-editor
2. open desktop -> unity -> panel
3. set systray-whitelist to "['all']"