//click line button
public void HandleLineButtonClick(object sender, System.EventArgs e)
{
_presentationModel.IsLineButtonEnabled = false;
_presentationModel.IsRectangleButtonEnabled = true;
_presentationModel.IsEllipseButtonEnabled = true;
_presentationModel.IsArrowButtonEnabled = true;
RefreshModeButton();
_model.SetMode(LINE);
}