musescore/MuseScore — pull request #819 by BartlomiejLewandowski (2014-04-05 19:54:29+00:00)
Title: Added changing of clef when switching to a different instrument

Added code that changes the clef, when an instrument has been changed in the staff properties.
Unfortunately, the optional template is not yet available, so I had to go with std::pair, where the first boolean is true when the instrument has been changed, and the second member is the actual clef.