I opened Monitor Preferences dialog in Ubuntu MATE 16.04.1 on Raspberry Pi 3 and clicking on Rotation button shows only Normal option. Is there a way to set portrait (90 degrees rotation) mode?
EDIT
Adding display_rotate=3 line to /boot/config.txt file, rotates the display, but I would prefer GUI configuration to work as well.
display_rotate=3really rotate the terminal for you? It doens't work for me on Ubuntu server. – Hola Soy Edu Feliz Navidad Oct 13 '19 at 09:10