title: How to check the correct radio button in MFC if the tab order has been changed
body: <p>I have this COM control with a group of radio buttons, which is associated with an integer variable to identify the checked radio button.</p>
  
  <p>This associated variable is saved/loaded through DoPropExchange(), therefore, backward compatibility is a must, i.e. the checked radio button saved by old version should be able to be carried over to the newer version, even though in the newer version, the tab order of the radio buttons have been changed.</p>
  
  <p>But after I added additional radio buttons into the group and changed the tab orders, when I was trying to load an old version of this control, there is no radio button checked! I ran it in debug mode and found that the associated integer was correctly loaded. </p>
  
  <p>Thanks in advance!
  James</p>