Clear piano roll from colors when switching instrument

qtgui/verticalpiano.py

@@ -163,6 +163,9 @@ class _VerticalPianoScene(QtWidgets.QGraphicsScene):
         api.callbacks.instrumentStatusChanged.append(self.instrumentStatusChanged)
 
     def clearVerticalPiano(self):
+        for colorKeyObj in self.colorKeys.values():
+            colorKeyObj.hide()
+
         self.allHighlightsOff()
         for nl in self.numberLabels:
             nl.setLabel("") #reset to just number