[QUOTE]Originally posted by Jos Maas:
[B]Vquestor, is this about detuning individual notes, like the two notes per octave that are detuned half a semitone in Arabic scales?

Yes.
If it is possible, an ideal situation would be for you to create a small icon of a one octave keyboard, where the detuned notes
are highlighted, and a row of preset buttons
that activate the customized scales(including
a default to normal button). The option of
naming these scales would also be nice.
Where this can become a real can of worms, is how you will detune the notes. The inferior way of using pitch bend messages (using already available programs) should be avoided.
Instead, the Midi Tuning Standard(MTS) should be implemented, or even better yet,
Yamaha's sysex for scale tuning.