The manifest editor is currently preffed off. Once it is ready, remove the pref.
Created attachment 821115 [details] [diff] [review] Enable Manifest Editor by default Just lining this up for review ahead of time... I won't attempt to land this until all dependencies have landed of course.
Alex, hopefully you can review this soon... Should be extremely fast! :)
Created attachment 8342562 [details] [diff] [review] Enable Manifest Editor by default v2 Carrying over Paul's r+ from attachment 821115 [details] [diff] [review]. Rebased. Try: https://tbpl.mozilla.org/?tree=Try&rev=5417ac009adf
Verified as fixed on latest Aurora 28.0a2 (20140122004004) for the pre-beta sign off under the next OSs: Windows 7 64-bit, Windows 8 32-bit, Ubuntu 13.04 64-bit, Mac OSX 10.8.5.