title: Change the size of a fill sample in Matlab legend
body: <p>I'm creating a plot in matlab that includes some lines, as well as a fill.  For example, </p>
  
  <pre><code>fill([0 1 1], [0 1 0], [.9 .9 .9]);
  plot(rand(5, 1), 'b');
  plot(rand(5, 1), 'r');
  plot(rand(5, 1), 'g');
  legend('fill', 'line one', 'line two', 'line three');
  </code></pre>
  
  <p>I can change the length of the sample lines in the legend with: </p>
  
  <pre><code>f = findobj('type', 'line');
  set(f(2), 'XData', [.2, .3]); % Changes line three
  set(f(4), 'XData', [.2, .3]); % Changes line two
  set(f(6), 'XData', [.2, .3]); % Changes line one
  </code></pre>
  
  <p>But this method doesn't seem to work for the fill. How do I change the size of the fill sample in the legend?</p>