This doesn’t seem to be possible at present - unless I’m missing something:
To have an additional mini version of the main event display window on a second or third screen to use as a visual reference for performers who can’t seen the main screen - in a vocal booth etc.
Or just to have the ‘project overview’ area movable (and sizable), so it can be dragged to another screen for the above reason.
At present the only way seems to be cloning the entire GUI to the additional screens via the OS - which doesn’t work if/when the screens are lower res than the main screen.