Rated 5 out of 5 stars
This is a 'must-have' addon for TB, In my opinion. I only use one aspect of Mnenhy, however, and that is the ability to select the exact headers that I want displayed. I need to see the CC headers for my emailing purposes--I need to see everyone who received the email that was sent to me. Without Mnenhy, I have to enable the massive 'full headers' to do this, and that takes up a large part of my screen. With this addon I can specify the CCs and any other parts of the header to show, and TB will ONLY show those headers.
This can be used with the addon Compact Header, which allows further customization of the header window. Mozilla's inane idea to put redundant and ugly big buttons within the header space makes these two extensions mandatory.