title: Handle negative time spans
body: <p>In my output of a grid, I calculate a <code>TimeSpan</code> and take its <code>TotalHours</code>. e.g.</p>
  
  <pre><code>(Eval("WorkedHours") - Eval("BadgedHours")).TotalHours
  </code></pre>
  
  <p>The goal is to show the <code>TotalHours</code> as <code>39:44</code>, so I need to convert the value from <code>7.5</code> to <code>07:30</code>. This is no problem... unless it's negative!</p>
  
  <p>I can create a <code>TimeSpan</code> object from <code>Hours</code> with </p>
  
  <pre><code>TimeSpan.FromHours( (Eval("WorkedHours") - Eval("BadgedHours")).TotalHours)
  </code></pre>
  
  <p>If it's negative, I can't convert it to a <code>DateTime</code> to use the <code>.ToString("HH:mm")</code> method, and the <code>TimeSpan</code> object does not support the format string.</p>