title: WPF Multiline TextBox for large content
body: <p>In a WPF application, I want to build a "Find in Files" output pane, in which I can stream large quantity of text, without re-allocating memory at each line, like the <code>TextBox</code> would do.</p>
  
  <p>The WPF <code>TextBox</code> has a single <code>Text</code> property which stores a contiguous string.  Each time, I want to add content, I need to do <code>textBox.Text += "New Text"</code>, which is bad.</p>
  
  <p>Ideally, that control would be virtual and require a minimum of resources, just for the visible lines.</p>
  
  <p>I thought about using a standard <code>ListBox</code> with a <code>VirtualizingStackPanel</code>, but it does not allow Text Selection across lines.</p>
  
  <p>(At each new line added, I want the control to update)</p>
  
  <p>Any suggestion?</p>