Shift GTK-3/ Geary Buttons to the left on linux mint

This works on the latest Geary

Manually :

Install dconf-editor

 sudo apt install dconf-editor 

open it up by typing dconf-editor.

Go to : org / cinnamon / desktop / interface / gtk-decoration-layout

and on the right find the button layout key setting.

the current string set there is expected to be : menu:minimize,maximize,close

change that to : close,minimize,maximize:menu

That’s it, you’re done.