I use often backup and restore some files via buttons.
How can I configure ONE button, which offers "Backup" and "Restore" via popup and then execute specified operations? Actually I use two buttons for each option, but ist would be nice to have this in one user command.
Isn't that what a menu with two options gives you?
You click the button which opens the menu, giving you the choice of Option 1 and Option 2, then you click one of the options (menu items) and their commands are executed.
If you put in in the top menu, where "file", "edit", "view" etc. is, as a menu, you can put both functions into the submenu & navigate per keyboard between them. If you use descriptive names, you can identify them easily.
Have you looked at using the @keydown modifier for your button commands? Where pressing the button does one command, holding SHIFT down and pressing the button does something else, and holding CTRL down while pressing the button does a third thing.
Or perhaps a three button button where a left mouse press does one thing, a right mouse press does something else, and a middle mouse press does a third thing.