Sometimes tag info is available in some external text file only. So the easiest way to populate tags is to use copy-paste. However this workflow is not quite convenient now.
The main problem is that 'edit focus' disappears from main window table as soon as you switch to some other window. So every time you switch windows to copy next track title you have to click (sometimes even two times!) the track to start editing.
The easiest way to fix it IMO would be to keep 'edit focus' when switching to other window.
Yet other (worthy on its own?) option is to have Next/Previous navigation buttons in Edit tag info dialog. So it would be possible to edit consequently titles of the tracks without that much clicking.