title: Undo in RichTextBox does not undo Pasted Text
body: <p>I have a WinForms RichTextBox and by default the Undo works for most things, but when I Paste some Text in (I have stripped it of formatting it is just plain text), and try undo it does not undo the text just pasted.</p>
  
  <p>Any help to a solution?</p>