private void EnsureElements(NavigationView navigationView) { if (_navHeaeder == null) { _navHeaeder = VisualHelpers.GetVisualChildByName <FrameworkElement>(navigationView, "HeaderContent"); } if (_menuButton == null) { _menuButton = VisualHelpers.GetVisualChildByName <FrameworkElement>(navigationView, "TogglePaneButton"); } }