[feature request] Maintain icons order

[eugene-rom]

As gnome shell disables extensions on screen lock, after unlock order of icons in tray may change.
If possible, try to maintain icons order.
Maybe save icon order to disk on "disable" event, and restore on "enable".
Or just sort icons by its wm_class.

Or better add ability to specify priority for wm_class, and then place icons in order of its priority, this will help maintain order between system restarts without having to persist state on "disable" event.