private static void HandlePreviewGotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
if (FocusScopeManager.Instance.ShouldDenyFocusChange)
{
e.Handled = true;
return;
}
DependencyObject newFocusObject = e.NewFocus as DependencyObject;
// if there is a newly focused object and it is not allowed focus
if (newFocusObject != null && !FocusScopeManager.GetAllowedFocus(newFocusObject))
{
// Push focus back to the client's desired focus sink and cancel the change
// of focus to new focus.
FocusScopeManager.Instance.ReturnFocus();
e.Handled = true;
}
}
private object CoerceFocusedElement(object newFocus)
{
UIElement newFocusElement = newFocus as UIElement;
if (newFocusElement != null)
{
// If we have been told to deny the next focus change then do so
if (this.ShouldDenyFocusChange)
{
this.EndDenyNextFocusChange();
return(DependencyProperty.UnsetValue);
}
// Don't allow logical focus to go to elements that are not focusable.
if (newFocus != null && !FocusScopeManager.GetAllowedFocus(newFocusElement))
{
return(DependencyProperty.UnsetValue);
}
}
return(newFocus);
}
