Rated 3 out of 5 stars
Haven't tested fully yet, but noticed that when reading emails the whole headers area is now hidden so you cannot see e.g. From, To, Subject.
Errors in console:
TypeError: gFolderDisplay is Null
TypeError: cal.itip is undefined
Using TB 17.0.6 and Lightning 1.9.1 on Windows XP SP3
Great idea though!