How do I modify the 3 dots menu?

[Yosey_Escalona]

Can I add or remove some options to the 3 dots menu that appears at the top right corner??

[TIMAI2]

See here:

Drei Punkte Menü

You can make your own title bar with a horizontal arrangement and use a button with a three dot image to call a spinner selection. See here for an example: Who Needs a Sidebar Anyway ?