Insert new key signature at instrument change if there is a change of transposition

Currently when an instrument change involves a change of transposition e.g. Bb clarinet to A clarinet, although the pitch transposition is handled correctly, the key signature is not updated automatically, the sharps and flats relevant to the new transposition are shown as accidentals. The workaround is to manually add the (current) key signature at the same point as the instrument change. It would be useful if this could happen automatically. It would need to be disabled where there is no change of transposition e.g. From flute to oboe.