public void DrawGrid()
        {
            // Draw grid lines
            for (int i = -400 / (int)this.CanvasScale; i < 400 / (int)this.CanvasScale; i++)
            {
                // x line
                this.DrawLine(new Point(this.Canvas.ActualWidth * -1, i), new Point(this.Canvas.ActualWidth, i), DefaultBrush, NormalThickness);
                // y line
                this.DrawLine(new Point(i, this.Canvas.ActualHeight * -1), new Point(i, this.Canvas.ActualHeight), DefaultBrush, NormalThickness);
            }

            // Draw two main lines
            // x line
            this.DrawLine(new Point(this.Canvas.ActualWidth * -1, 0), new Point(this.Canvas.ActualWidth, 0), AttentionBrush, NormalThickness);
            // y line
            this.DrawLine(new Point(0, this.Canvas.ActualHeight * -1), new Point(0, this.Canvas.ActualHeight), AttentionBrush, NormalThickness);
        }