C#

if(excelApplication != null && excelApplication.Workbooks.Count > 0)<br />
{<br />
    foreach(Workbook wb in excelApplication.Workbooks)<br />
    {<br />
       wb.Close(false,Type.Missing,Type.Missing);         <br />
    }<br />
    excelApplication.Quit();<br />
    excelApplication.Visible = false;<br />
}

<br />
public void OnPaint(object sender,PaintEventArgs e)<br />
		{<br />
			Graphics g=e.Graphics;	<br />
			Pen pen=new Pen(Color.Magenta);<br />
			Point p1=new Point(index1,index2);<br />
			Point p2=new Point(index3,index4);<br />
			g.DrawLine(pen,p1,p2);			<br />
		}	<br />
<br />
public void mouseUp(object sender,MouseEventArgs e)<br />
		{<br />
			index3=e.X;index4=e.Y;		<br />
			this.Paint+=new PaintEventHandler(this.OnPaint);	<br />
			Invalidate();<br />
		}<br />
		public void mouseDown(object sender,MouseEventArgs e)<br />
		{<br />
			index1=e.X;index2=e.Y;					<br />
		}<br />