title: WPF, Validation on request
body: <p>I'm writing an entity editor in WPF. Obviously, I have a few rules to data being edited, such as some of them may not be null, match regular expression etc. However, I'd like the validation to be performed after first attempt to confirm changes, such that user is not faced with an editor with all fields marked as red from the beginning (for instance, those, which are initially empty and should not be empty).</p>
  
  <p>How can I do that? Or is there a different solution for this problem?</p>