Review for CompactHeader by Bruce Fraser
Rated 5 out of 5 stars
CompactHeader may have had problems recently (according to Nemo_bis), but it's working fine now in Thunderbird 38.2. It was updated September 16, 2015, so that may have been the fix.
This review is for a previous version of the add-on (2.1.0).To create your own collections, you must have a Mozilla Add-ons account.