Bug with last Version ! Rated 1 out of 5 stars
Switch from Firefox-Profil A to Profil B( Profil A closed), open Link in Thunderbird.
I have 2 windows: Firefox Profil A and B !
TB-Link opening in Window with Profil A, thats not correctly !
Edit: No, with 188.8.131.52 Version same problem !
Hopefully this should be fixed in 184.108.40.206 version. To try it, you must install the latest version in all your profiles.