Panda 0.15.1 matplotlib 1.4.2 setting default font.size messes up labels.
```
import pandas as pd
import matplotlib.pyplot as plt 
import matplotlib as m

print 'Matplotlib version:', m.__version__
Matplotlib version: 1.4.2
print 'Pandas version:', pd.__version__
Pandas version: 0.15.1

plt.style.use('ggplot')
m.rc("text.latex",preamble=r"\usepackage{cmbright}") 
m.rcParams['font.size'] = 20               ###<--- This line causes trouble.
```
## df is a pandas dataframe

1) it messes up the following:

```
df.boxplot("column name",by="splitcol")
```

The heading and subheading overlap.

regards
