title: In Crystal Reports, boolean parameter to select both true and false
body: <p>Using CR 2008. </p>
  
  <p>I have a Boolean parameter with true and false values which works fine.  Is there a way to add a third option to show both such as 'True, False, Show All'? </p>
  
  <p>Without setting the parameter to allow multiple values.  I.e. By setting the parameter to allow multiple values I can then just select both true and false. Not what I want - I want 3 single options as mentioned above. </p>
  
  <p>Thanks in advance. </p>