public BrowserWidget()
{
this.InitializeComponent();
tabView.Loaded += OnStart;
tabScrollViewer.RegisterPropertyChangedCallback(
ScrollViewer.ScrollableWidthProperty,
tabScrollViewer_ScrollableWidthChanged);
App.AddBrowser(this);
tabHandler = new TabHandler(pageViewer, tabButtonsStackPanel);
tabHandler.OnNavigationStart += HandleNavigationStart;
tabHandler.OnNavigationComplete += HandleNavigationComplete;
tabHandler.OnCloseTabClick += HandleCloseTabClick;
}