Multi-Item Edit v3.0 will display the selected track(s)'s tags in a single window for viewing or editing. When working with two or more tracks, the common tags of the selected tracks are initially displayed; when a single track is selected then it displays all tags for that track.
This latest version, first and foremost, will recognize a single selected track. And because it now also stays active and floating above iTunes until quit (no longer quitting after applying changes), you can cursor through tracks in a playlist to view or edit them individually.
I also added auto-complete to the Genre field, added Close and Miniaturize control buttons to the window, improved accessibility tabbing between text and option fields, improved the UI logic between Plays/Skips and Last Played/Last Skipped fields, and made other minor tweaks.
Multi-Item Edit v3.0 is a free update for registered users, free to try full-featured for ten days, $1.99 to purchase. OS X 10.8 or later.