private void btnLogout_Click(object sender, RoutedEventArgs e) { MessageBoxResult result = MessageBox.Show("Đăng xuất ?", "Question", MessageBoxButton.OKCancel); switch (result) { case MessageBoxResult.OK: User_Control_BUS control_BUS = new User_Control_BUS(); Data_Context.currentAccount = null; Data_Context.currentUID = null; Data_Context.currentHomePageBook = null; IsLogout = true; Window1 Login = new Window1(); Window.GetWindow(this).Close(); Login.Show(); break; case MessageBoxResult.Cancel: break; } }