Allow user to select flats or sharps for enharmonic key signatures
Example: When you enter a key signature of C-flat into a score the B-flat instruments have a key signature of D-flat. If the composer prefers a key signature of C#, then you must use a workaround that can get confusing.
I propose that there be either radio buttons or a dropdown that allows the user to Prefer Sharps or Flats in the transposition section of the staff/parts properties window. A dropdown might be best, because you can add the option of default.