Is it possible to change the order of icons shown in the indicator applet? With Tomboy indicator, Weather indicator, Clipboard-manager indicator, Ubuntu One and Dropbox indicators and a Battery Status indicator in addition to the classic Messages indicator and Sound Menu indicator my Indicator Applet becomes a little bit messed up, sorting the icons would help a lot...
The system indicators are in a fixed order by design. While you might not like the order, it makes support easier by having a fixed order (we can argue about the order endlessly). The application indicators work a little bit differently, they're designed so that there is a default order but applications can adjust that for continuity. For instance, if an application had two indicators that it wanted next to each other.
Because this system leads to a possible abuse by application developers there is a set of overrides in the system. The first is at the system level so that it can be managed by packages once the distro figures out there is an abusing application it can be fixed for all users. It's located at:
You can put any status notifier ID in there and give it a new ordering index that will because the new index for that application. There is also a per-user override file that can exist in your home directory at:
Hopefully that will give you some help in adjusting your panel the way that you prefer!
The official ubuntu ones (weather, ubu-one, battery, messages, me, sound, shutdown) are hardcoded in place. Sucks. The other ones should take their order using the law of first come first serve, right-left precedence. Judging from this brainstorm/feature request, the answer is: No, you cannot manually change the order of icons via the gui. But see @Ted Gould's answer.