title: Applying styles to the headers of pandas-generated excel files
body: <p>Reviewing <a href="https://stackoverflow.com/users/2726279/tim-hoffmann">Tim Hoffman</a>'s  answer to <a href="https://stackoverflow.com/questions/24065547/apply-styles-while-exporting-to-xlsx-in-pandas-with-xlsxwriter">this broader question</a> made me want to make my headers wrap.</p>
  
  <p>I tried this with the following code:</p>
  
  <pre><code>import pandas.core.format
  pandas.core.format.header_style["alignment"].update({"text_wrap" : True})
  pandas.core.format.header_style["font"].update({"bold" : False})
  </code></pre>
  
  <p>Now, the actual result is NOT bolded, so I know I'm managing to overwrite the default. However, the text is not wrapping.</p>
  
  <p>Based on what I see in the <a href="http://xlsxwriter.readthedocs.org/format.html#set_text_wrap" rel="nofollow noreferrer">xlsxwriter format class guide</a> and that there's already an <em>alignment</em> keyword...</p>
  
  <pre><code>ipdb&gt; pandas.core.format.header_style["alignment"]
  {'horizontal': 'center', 'vertical': 'top'} 
  </code></pre>
  
  <p>...and that after I modify it as per above...</p>
  
  <pre><code>ipdb&gt; pandas.core.format.header_style["alignment"].update({"text_wrap" : True})
  ipdb&gt; pandas.core.format.header_style["alignment"]
  {'horizontal': 'center', 'text_wrap': True, 'vertical': 'top'}
  </code></pre>
  
  <p>...I would expect to get the result, but I'm not. Anyone know why?</p>
  
  <p>I gather that I could also re-write the data using an xlsxwriter write method, but that feels like more work to me, so I'm hoping to make it work <em>this</em> way.</p>