title: IsTabStop="False" has no effect on my WPF app
body: <p>I'm having a really hard time with something that should be trivial. I just want to remove a few buttons from the tab order on a UserControl. I've tried adding <code>IsTabStop="False"</code> and <code>KeyboardNavigation.IsTabStop="False"</code> attributes to their xaml declarations, as well as setting <code>myButton.IsTabStop = false;</code> in the Loaded event handler for the UserControl. None of these additions had any effect, I could still tab to the controls I did this for. </p>
  
  <p>Setting the TabIndex in the xaml works fine. The UserControl is being displayed in a WPFElementHost if that might make a difference. The other thought I had was that I might need to specify the TabIndex for all the other controls, but I haven't read that anywhere and I'd prefer to not state that explicitly if possible. Does anyone have a guess as to what might be going wrong?</p>