Checking which voice a note belongs to
When you select one single note, the corresponding voice button on the extended toolbar is selected. This allows you to quickly find out which voice a certain note is in (after you have used the Move To Voice function, for example).
When you step through the notes using the Left Arrow/Right Arrow keys, you only step through the notes in one voice at a time.
This can be used as a quick way to check which notes belong to the same voice as some other note.