public void ToolMouseDown(object sender, MouseEventArgs e) { if (e.Button == MouseButtons.Left) { lineSegment = new LineSegment(new System.Drawing.Point(e.X, e.Y)); lineSegment.Endpoint = new System.Drawing.Point(e.X, e.Y); canvas.AddDrawingObject(lineSegment); selectedRectangle = this.canvas.GetRectangleObjectAt(e.X, e.Y); lineSegment.xstart = e.X; lineSegment.ystart = e.Y; if (selectedRectangle != null) { //implemented later } } }