Hello there

Go to the task manager.(ctrl`shift`esc.) Can I ask if you already tried to fix this issue , by just using the normal buttons? What and how do or does it react? Can you open task manager and go in to that taskmanager and find the thunderbird.exe in that process tab? Right click on that thunderbird.exe and maximize screen with these mouse clicks. Use the option to maximize that screen. Can it?

Greetings

Hello there

I can offer you to use trouble shoot mode for thunderbird. Start the program in that troubleshooting mode and see and check for some add ons that can be there to block that process as that add on is not working correct for that thunderbird software and that add on is the culprit . Try to find that no good add on and remove it if that screen is going back to normal proportions in that troubleshoot mode. https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

Is it screen going back to normal?

My question is to you Marshall , how does it react? How is that screen reacting if you try to use the normal buttons?

Greetings.

Hello there

You can find the editor to enter some text. Go to thunderbird and open settings and find config editor. Find : layout.css.devpixelsperpx: Try to change the value to what you like to change it into a better screen proportion. And restart that program to take changes.

For further fixes it can become that the screen configuration for that os have to be changed to what it can solves there for that minimized screen.

Question are open