title: Check width of TextBlock after content changed
body: <p>I have some <code>TextBlock</code>, that can display very long string.</p>
  
  <p>However, when <code>TextBlock</code> <em>content</em> <code>width</code> become greater than <code>TextBlock</code> own <code>width</code>, i want to cut some part of content and place "..." at the end instead.</p>
  
  <p>I will display full content as <code>TooTtip</code>.</p>
  
  <pre><code>&lt;TextBlock Text="{Binding Path=MyValue}" TextAlignment="Right" FontWeight="Bold" ToolTip="{Binding MyValue}" /&gt;
  </code></pre>
  
  <p>As far as i know TextBlock have no events, that can fire after content changed. Is there any good approach to listen something like <code>contentChanged</code> event on TextBlock, calculate text width, compare with control width and cut part of content that not fit?</p>
  
  <p>I need to do it in codebehind, because viewmodel cant be changed some reasons that not matter.</p>