title: Remove specified text from beginning of lines only if present (C#)
body: <p>I have a textbox in which the user can edit text, in a scripting language. I've figured out how to let the user comment out lines in one click, but can't seem to figure out how to uncomment properly. For example, if the box has:</p>
  
  <blockquote>
  <pre><code>Normal Text is here
  More normal text
  -- Commented text
  -- More commented text
  Normal Text again
  --Commented Text Again
  </code></pre>
  </blockquote>
  
  <p>So, when the user selects any amount of text and decides to uncomment, the "--" is removed from the beginning of the lines that have it. The lines without the "--" should be unaffected. In short, I want an uncomment function that performs similar to the one in Visual Studio. Is there any way to accomplish this?</p>
  
  <p>Thanks</p>