I am sure the configuration of `matplotlib` for python is correct since I have used it to plot some figures.

But today it just stop working for some reason. I tested it with really simple code like:

```
import matplotlib.pyplot as plt
import numpy as np
x = np.arange(0, 5, 0.1)
y = np.sin(x)
plt.plot(x, y)

```

There's no error but just no figure shown up.

I am using python 2.6, Eclipse in Ubuntu