Comment 28 for bug 334344

can you right click the .xpi than click save as (save it somewhere) than use thunderbirds add extension and select that? That is how you normally install extensions for Thunderbird. if you click it normally to install it it defaults to Firefox. That is normal and has been that way for a long time. If we get it in repos than installing the .deb will add it to Thunderbird. Assuming he lists depends on thunderbird I'm not sure that firefox should be a depend however i wouldnt use anything but Thunderbird and maybe Seamonkey mail news.
This would be great to have in repos.