title: How to render whitespaces as dots in WPF RichTextBox?
body: <p>I need the way to render regular space, nonbreaking space and some other formatting characters (like left-to-right mark) like MS Word renders them, when you choose to show non-printable characters.</p>
  
  <p>I tried two approaches:</p>
  
  <p>1) Replace characters with rarely used characters.
  It works, but in this case we loose "nonbreaking" behavior of nonbreakable space (and LTR and RTL marks also stop working)</p>
  
  <p>2) Use the custom font</p>
  
  <p>It allows to preserve special behavior of nonbreaking space and LTR/RTL marks, but for some strange reason WPF renders nonbreaking space with usual space glyph.</p>
  
  <p>WinForms RichTextBox renders text with the same font correctly.</p>
  
  <p>This problem could be solved with applying different font with different space glyph for spaces and nonbreaking spaces, but LTR and RTL marks are not rendered at all even if I add glyph for them.</p>
  
  <p>Have you any ideas how I could render that characters with visible glyph preserving their "LTR", "RTL", "nonbreaking" behavior?</p>