'Return a TreeWidgetItem suitable for displaying/controlling the content of
this parameter. This is called automatically when a ParameterTree attempts
to display this Parameter.
Most subclasses will want to override this function.'

def makeTreeItem(self, depth):

    if hasattr(self, 'itemClass'):
        return self.itemClass(self, depth)
    else:
        return ParameterItem(self, depth=depth)
