For years we nolonger can change (increase) the font size of the thunderbird email messages listing on inbox messages (NOT the email itself). In the old days there was an extension called; themes & font size changer. Then you changed the interface for extensions and it no longerr worked. Nothing has ever worked since. After years of not using thunderbird I switched to Evolution. However recently I did find a way to do what I wanted by using the terminal window to launch thunderbird and increase the font using 'GDK_DPI_SCALE=2 thunderbird' as a terminal line command. Is this the ONLY way to increase the font of the thunderbird email directory listing of input emails? The fact that Mozilla never implementes the Simple approach of using Ctrl + and Ctrl - to increase and decrease the font as many other apps do, is beyound me. I'm not a novice, and have been a system software developer for over 30 years and used Unix in 1976 when it was from original developer Bell Labs. So what can I do other than the terminal command? I currently use Linux Mint 21.2 cinnamon and thunderbird 115.9. Attached is the nice large font directory inbox listing I get from running thunderbird from a terminal comand changing the GDI scale as indicated above.