When unmaximised, it’s certainly capable of this:
However, when maximised, it loses this ability:
…but it doesn’t matter much anyway, because the subject column is so compressed and impossible to uncompress:
Consequently, how do I permit the columns to render outside the viewport, like I can in KDE’s Dolphin file manager (as an example):
This sounds like a support question - the link to support is seen in Useful Thunderbird Links
Posted at https://support.mozilla.org/en-US/questions/1463493, but it appears that Markdown isn’t accepted, so it shan’t be of much use. Thanks, though.
Thanks for pursuing this feature. For the record, this is implemented in https://bugzilla.mozilla.org/show_bug.cgi?id=381821
