version 0.12.0: problems interacting subplots and DataFrame().hist()
I run Python 2.7.5 on Windows 7 64-bit and IPython 0.13.2.

I have a data frame with some portfolio weights and I do the following:

```
def weight_histograms(field, name, bins=100):
    if flag_inline:
        plt.figure(figsize=(16, 8))
    else:
        plt.figure()
    plt.subplot(121)
    portfolio_data[field].hist(normed=True, bins=bins)
    plt.title('{}: All'.format(name))
    plt.subplot(122)
    portfolio_data.ix[portfolio_data[field] != 0, field].hist(normed=True, bins=bins)
    plt.title('{}: Non-Zero'.format(name))
```

With pandas 0.11.0, running

```
weight_histograms(field_benchmark_weight, 'Benchmark Weights')
```

in IPython with 

```
%pylab inline
```

and

```
flag_inline=True
```

I get

![pandas0 11 0](https://f.cloud.github.com/assets/1903683/882420/59ad630a-f962-11e2-94e0-3ade62951d54.jpg)

Doing the same thing with pandas 0.12.0 results in

![pandas0 12 0](https://f.cloud.github.com/assets/1903683/882423/68766666-f962-11e2-80be-9131f5f0d03d.jpg)
