Avaliado em 4 de 5 estrelas
I was too harsh on my previous review, the changes that the add on impose must be manually reverted if the addon was uninstalled, before uninstalling it is possible to automatically revert the changes and then uninstall.
I believe this problem must be addressed by Thunderbird and how it handles add-on installation/uninstallation. And hope the developers are filing an issue with Mozilla.
Regarding the addon itself, so far so good, gives the threads a look more modern than the plain Thunderbird style.