import pandas hangs save file matplotlib dialog
Hello, such code

``` python
    import pandas
    import matplotlib.pyplot as plt
    plt.plot([1, 2, 3])
    plt.show()
```

freezes  matplotlib file save dialog (the same issue with wxpython FilePickerCtrl).

![pyplothang](https://cloud.githubusercontent.com/assets/4736996/5553536/bd49ddae-8c2c-11e4-8084-0ba68d378550.png)

What is the reason of such issue? How to avoid it?
