How can I use the Alt + right click shortcut in Ubuntu 17.xx and higher without installing additional software?
You could use Alt + Shift + <Right Mouse Button> instead.
(This shortcut is normally not used by the system.)
This will have the same effect, except the "Shift" key will make it add the new selection to an already existing one.
So what you should do is:
1. Press A (if needed) to remove any old selections.
2. Press Alt + Shift + RMB.