How do I set the panel whitelist back to the default?

I set this option:

gsettings set desktop.unity.panel systray-whitelist "['all']"

and now I am having all sorts of weird problems with my panel like double icons and stuff, how do I reset this setting to the default setting?

Try installing the dconf-tools from software center.

Press ALT + F2 to run a command and search for dconf-editor

Highlight the whitelist entry as shown in the picture and click the Set To Default button.

Log-off and login for the change to take effect.

No need 'all' in value.. just add the command of application in the whitelist value like 'skype' or whatever you wont and logout. For me it worked nice and missing indicator was on the right place

In 12.10 systray-whitelist seems to be in com.canonical.unity.panel, as shown below: