title: TabControl losing selected tab on Window.Show
body: <p>We have an MVVM (Cinch) solution that has a Window with a TabControl in it.  The ItemsSource is bound to a CollectionView (DefaultView generated from an ObservableCollection), with IsSynchronizedWithCurrentItem=true.  Everything works great the first time the Window loads... tabs are displaying correctly and the user can switch between them.</p>
  
  <p>The problem occurs when the Window is hidden and shown again.  The first tab is always selected again, regardless of what the CurrentItem in the CollectionView is.  The line before the .Show has the CurrentItem as the tab we want, but the tab switches during the .Show operation.</p>
  
  <p>Has anyone else run into this issue?</p>