title: How to prevent/cancel a combobox's value change in c#?
body: <p>I have a combobox at the top of a form that loads editable data into fields below.  If the user has made changes, but not saved, and tries to select a different option from the combobox, I want to warn them and give them a chance to cancel or save.</p>
  
  <p>I am in need of a "BeforeValueChange" event with a cancelable event argument. </p>
  
  <p>Any advice on how to accomplish?</p>