Window will no longer resize after recent update
The primary multi-pane viewing window will not resize after the latest update (no diagonal arrow when hovering over lower right corner, no other apparent control to resize vertical or horizontal).
All I can do is switch between full screen, and what was apparently my last saved smaller size (not very much smaller than full screen), but I would greatly prefer to make this application occupy only half a screen (top half of a vertical split), as is my usual layout for multitasking.
I've tried Safe Mode, Toolbar reset, and also disabling all Add-ons (only using 2 presently), etc., but the problem persists throughout.
Alla svar (3)
If you right-click the taskbar, Show windows stacked, are the windows still not sizeable? Try also opening the profile folder from Help/Troubleshooting, click Open Folder, close TB, and delete session.json.
Thank you for the quick advice, unfortunately neither stacked windows nor the profile "session.json" file deletion/relaunch solved the issue. All other program windows do scale properly, but Thunderbird doesn't present the option.
Try this: Help/Troubleshooting, about:profiles, create a new profile and launch it. This profile won't have any data, and there's no need to add an account, but see if the window resizes as expected.