I have just downloaded a new version of Thunderbird, and the interline spacing is now too big and takes up too much of the screen, allowing less to be seen.
Interline spacing now too big [headers and messages]
Alla svar (1)
Did you previously have these things customized with a userchrome.css file of an add-on?
I am not aware of any significant changes in TB60 regarding line heights in lists.