Thank you for your comments. Yes, I have looked at the tab produced by some other programs, and seen the lack of consistency.

HARMONY already places the standard score above the TAB. (Actually, to be more accurate, it places the Tab below the score). In fact, it is not possible at present to show the tab without the score, because all horizontal positioning is dependent on the score. Changing this would be a major exercise.

This does mean you get aligned lyrics as well, though.

HARMONY uses a proper music font, not ASCII, for score display, and draws lines for the TAB elements, apart from numbers.

Although the program 'suggests' tablature, you can manually override the string assignments for each note. This doesn't seem to be needed too much, although I am not enough of a guitarist to decide.

However, I think it is much quicker to let the program do the work, then make a few changes, rather than to put everything in yourself.

By the way, I am not sure how you could override a fret position for a specific note, once the string has been chosen? However, a future version could implement 'fret windows' where you specify the 'to' and 'from' frets between which to place the note.

As for the timing of notes, I wondered whether this could be indicated by extra (vertical) tails, maybe double tails close together for 16th notes, triple for 32nd? Or maybe very short flags on the tails in the same way as standard score?

There is still the problem of indicating whole/half/quarter notes and dotted notes, as well as triplets.

Also, I have found it helpful to place the tails slightly to the right of the note numbers, so that they don't obscure other numbers within a chord. Does that sound a good idea?

Please let me know of your preferences, and any other essential features you need.