if (getSelectedObjects().isEmpty()
|| !(getSelectedObjects().get(0) instanceof MusicTreeEditPart)
|| ((MusicTreeEditPart) getSelectedObjects().get(0)).getModel() == null
)
return false;
MusicTreeEditPart selectedEditPart = (MusicTreeEditPart) getSelectedObjects()
.get(0);
if (!(selectedEditPart.getModel() instanceof MeasureForm))
return false;
return true;
}