I have been looking for a solution for the problem created after approving all updates from Ubuntu on 5/10.
Thunderbird updated to version 52.1.1 during the update done from Software Updater. After that, the sidebar, which displays the various email accounts and local folders has developed a problem with the fonts. They are very thin and difficult to see.
The main window, top menus, and email text do not seem to be affected. I tried setting the default fonts in "Appearance". But, this changed nothing.
I would like to either; A) return to Thunderbird 45.8 which was working nicely. or B) fix this font display problem
No other applications are having this problem. It seems isolated to Thunderbird only.
EDIT: I discovered that this problem also affects the terminal font. However, setting the default profile font in terminal options fixes that particular problem.
EDIT2: New 17.04 install with latest Thunderbird update also displays this problem. Concluding that the problem is not transient. Figured out how to go back to 45.8 and locked it until the problem is resolved.
Yep, I'm having the same problem. I have my appearance set as Mattinee, a dark theme, but now the messages panel in Thunderbird is a light theme. These problems came with the update to 52.1.1.