title: Managing an Errors/Status text box in C# WinForm
body: <p>I'm writing a UI for managing subtitle files, it offers some operations on the file and has an errors/status text box (which is actually a rich text box).
  I want to be able to add lines to the text box that indicate the status of a long operation, so I did the following:</p>
  
  <p><code>
  StatusErrors.Text += "Changing time tarted, subtitle file is being processed...\n";
  longOperation(StatusErrors);
  StatusErrors.Text += "Done\n";</code></p>
  
  <p>But the only text I see is "Done" at the end of the operation, why is that?</p>