Add ability to reorder indicators

[Owen Williams]

Right now it is only possible to reorder application indicators through the use of the ~/.local/share/indicators/application/ordering-override.keyfile. While not every user will need to reorder the indicators, this file is very hard to find and difficult to use, requiring the monitoring of indicator-application-service debug output to figure out how to create entries in that file correctly.

It should be possible to create a simple user interface to allow the user to reorder the indicators themselves. Doing this would rewrite the ordering hash for the current run, and rewrite the keyfile for subsequent logins. The method of ordering need not be particularly discoverable. Either old-style middle-click and drag could work, or alt-click and drag, or even a right click menu that leads to a preference window that allows dragging and dropping of indicators.

While this is a feature that not every user will need, users have reasons for a preferred order: grouping of similar indicators, moving an indicator to the end that constantly changes size, visual appeal, etc. Adding a simple, non-discoverable way to accomplish this more easily would be greatly appreciated.

[Matthew Paul Thomas (mpt)]

FWIW, Mac OS X uses Command+drag for this.