changing tunings midstream

Hi,

I just finished the book "Lies my music teacher told me." He mentioned
that good singers adapt the note to make the chords better. (This is
using normal western 12 note scales.) For example, in the key of C we
would have a C chord as C = 1, E = 5/4, G = 3/2. If we play a G chord
it would be G = 3/2, B = 15/8, D = 9/8. But if we play a Dm chord, we
have can't connect the D to the C by means of the G... so we use the F
instead. For a Dm chord we would have D = 10/9, F = 4/3, A = 5/3. Note
that D could be 10/9 or 9/8 depending on which chord we are playing. We
would need the tuning to adapt to which harmonization we are currently
using.

Is there any program out there that plays keyboard music like this? Is
there some way to listen to midi music with the tuning adjusted this
way?

John Berglund