Review for Compact Headers by Francois
Rated 5 out of 5 stars
Good replacement for "compact header", thank you very much!
One (hopefully small) feature request: instead of showing From and Subject in compact mode, allow showing Correspondents and Subject -- this way, you automatically see senders (for message you receive) or recipients (for messages you send), which is more useful information than seeing yourself as sender when viewing message you have sent.
To create your own collections, you must have a Mozilla Add-ons account.