There seems to be a FigureManagerQTAgg defined in backend_qt4agg.py, just wondering why its not used. [ref](https://github.com/matplotlib/matplotlib/blob/master/lib/matplotlib/backends/backend_qt4agg.py#L27)
There seems to be a FigureManagerQTAgg defined in backend_qt4agg.py, just wondering why its not used.
ref