public MainWindow() { InitializeComponent(); if (IsBuilderConnectionUnavailable()) { Application.Current.Shutdown(); return; } vm = new BuilderViewModel(); DataContext = vm; var s = new Style(); s.Setters.Add(new Setter(VisibilityProperty, Visibility.Collapsed)); tabControl.ItemContainerStyle = s; tabControl.SelectedIndex = 0; this.Closing += MainWindow_Closing; }