title: Selected Index Change on WPF combobox?
body: <p>I'm converting an app of mine from WinForms to WPF.  I came across this problem where in WinForms if I CLEAR a combobox, that does not fire combobox.selectedindexchange.  It only fires when the user actually changes the index.</p>
  
  <p>That's the functionality I need.  However in WPF I can only find combobox.SelectionChanged.  This unfortunately fires on both index change and clearing a combobox (any change).</p>
  
  <p>In WPF how can I only trigger an event when the user changes the index?  I'm assuming there's a solution I'm missing that's like the WinForms solution.  I'm trying not to play games with global variables and having to track what was previously selected....that's a mess.</p>
  
  <p>Mouseleave is also a mess.</p>
  
  <p>I would greatly appreciate any help!</p>