The screens panel replaces the thumbnails panel when one or more screens are opened. When two screens of the same type are opened, joint controls are added at the bottom.
Adding and removing screens can be done by using the main toolbar, the menu View or the close buttons on the screens themselves.
To swap the screens use the menuor the swap button in the joint controls.
More details about the playback screen user interface can be found at Playback screen user interface
More details about the capture screen user interface can be found at Capture screen user interface