Rated 5 out of 5 stars
Update: In Version 1.2 the problem still occurs, but it occurs a bit later comparing to v1.1. Initially it is working (even after closing/restarting Thunderbird), but at some point the option "Message Body as --> All Body Parts" vanishes from the menu and just won't come back. Please correct!
When downloading/installing this addon directly (through the addons tab) initially it works: I can see the option Message Body as All Body Parts.
However, when I close and restart Thunderbird, although the addon is enabled, the above option in the menu is no more there. You have to remove (disable/enable does not work) the addon and re-install to have the option again.
I have tried in three different computers with the same results.
Note: If I try to install from file (downloaded xpi) and not directly (through the Addons Thunderbird page), then the addon does not work: the option is not added to the menu at all.
Very useful addon, but please make it work!