After chatting to Matt about the omnibar API we realised that we both need the same thing. The ability to change the url bar for an add-on to show: [the puzzle icon] Add-on: [add-on name] In a colour that isn't confusing (eg: not green or orange). This means bug 1266012 will focus on the panel.
I thought this bug would be a shared bit of code between the omnibar and bug 1266012, turns out it isn't. I've already got this working in bug 1266012 so this bug serves no purpose.