'Instantiate an instance of FigureCanvasClass
This is used for backend switching, e.g., to instantiate a
FigureCanvasPS from a FigureCanvasGTK.  Note, deep copying is
not done, so any changes to one of the instances (e.g., setting
figure size or line props), will be reflected in the other'

def switch_backends(self, FigureCanvasClass):

    newCanvas = FigureCanvasClass(self.figure)
    newCanvas._is_saving = self._is_saving
    return newCanvas
