title: Change font increment for WPF RichTextBox
body: <p>I'm using a WPF RichTextBox control to input some text with user formatting capability, including font size adjustment.  The built-in commands for IncreaseFontSize and DecreaseFontSize will adjust the font size by 0.75pt each time the command is executed.  I would like to increase the granularity to 2pt.</p>
  
  <p>Can this be done without implementing my own custom commands?</p>