/// <summary> Handles the line button click. </summary>
///
/// <param name="sender"> Source of the event. </param>
/// <param name="e"> Routed event information. </param>
///
/// ### <remarks> Chen-Tai,Peng, 12/12/2018. </remarks>
private void HandleLineButtonClick(object sender, RoutedEventArgs e)
{
_model.ChangeToLine();
}
