Rated 3 out of 5 stars

If you use the Customize Header functionality to remove all the buttons (Reply, Archive, Delete, etc) - and then collapse the Header - there's a strange different-colored "box" of space where the buttons would go.
With the Header expanded normally, everything is fine. No weird box. But if you collapse the Header (and don't have any of the buttons on there) - then you see it.

This review is for a previous version of the add-on (1.1.4).