title: Event handler for groupBox with radioButtons in C#
body: <p>I have some radionButtons in groupBox and I need to do action what I could call "one of radiobuttons.checked changed" or find out from radiobutton what index is changed. 
  I've tryed to find it in list of events but I couldn't find the right one. </p>
  
  <p><strong>Edit:</strong> 
  To make it more clear: I need to know if exist some handel for what I'll write handler method for the goupBox not for single radioButton. I know how to use radiButton.checkedChanged, but it's not what I'm finding .. 
  Or differently I need to know what options have the groupBox in monitoring what happens inside this groupBox - I mean only the handlers for the groupBox. I'm finding handler "in the group box is something happens" or simimilar if any exist.</p>
  
  <p>
  It's in <strong>WFA (Windows Presentation Application)</strong> in Visual studio 2012.</p>