(FIXED) Notation bug - accidentals again (5.979+dev0705)

[bFooz]

Test rpp: https://drive.google.com/open?id=1XM...kMTxVhKhg0aazq

- set the note in the test project to "Notate as Bb"

BUG - the note stays as A#.

If I move the item in time, the note then becomes Bb.

[schwa]

This bug appears because the key signature (A natural minor) is enharmonic to C major, so the user preference to notate accidentals in C major is applied inconsistently. The next build will fix this particular case, but this is a surprisingly complex area so there could be unintended side effects to watch out for!

[Sambo Rouge]

Mon Dieu! The Muppet is back!

[bFooz]

There is this thing which is confusing:

-set key signature to 3#
-input G#
-change key sig. to 3b

UNEXPECTED: the note is changed to Ab

EXPECTED: the note stays as G#, because it was written like that

Use case:
I use different midi items for different song parts. When the whole piece is in a single key, the key sig. is placed in the first item. When I open only some of the latter items, there is no key sig. present in the editor so all notes are misspelled. As soon as I open also the first item with the key sig., notes are spelled ok. I have "Key sig. changes affect all tracks" OFF for cases when there are multiple key signatures present in a piece and I want to move, stretch, add music freely in time.