private void LogoutItem_Click(object sender, RoutedEventArgs e)
{
controller.LogoutUser();
BitmapImage bitmap = new BitmapImage(new Uri("Resources\\redndot.png", UriKind.Relative));
OnlineImage.Source = bitmap;
ChangeActiveButtons(false);
menuItemLogin.Header = "Log in";
menuItemLogin.Click -= LogoutItem_Click;
menuItemLogin.Click += new RoutedEventHandler(LoginItem_Click);
richTextBox.Document = new FlowDocument();
}