private void button4_Click(object sender, EventArgs e)

{

string filename = null;

if (OpenFileDialog1.ShowDialog == DialogResult.OK)

{

//Store Selected File Name In the Variable...

filename = OpenFileDialog1.FileName;

//Load Selected File Into The RichtextBox...

RichTextBox1.LoadFile(filename);

}

//Set The Form Title Name As Filename.....

this.Text = filename;

}