private void Form1_Load(object sender, EventArgs e)
{
    // This line suppresses the default context menu for the TextBox control. 
    textBox1.ContextMenu = new ContextMenu();
    textBox1.MouseDown += new MouseEventHandler(textBox1_MouseDown);
}

void textBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (e.Button == MouseButtons.Right)
    {
        textBox1.Select(0, textBox1.Text.Length);
    }
}

Point firstPoint;
Boolean haveFirstPoint;

public void EnableDrawing()
{
    this.MouseDown += new MouseEventHandler(Form1_MouseDownDrawing);
}

void Form1_MouseDownDrawing(object sender, System.Windows.Forms.MouseEventArgs e)
{
    if (haveFirstPoint)
    {
        Graphics g = this.CreateGraphics();
        g.DrawLine(Pens.Black, firstPoint, e.Location);
        haveFirstPoint = false;
    }
    else
    {
        firstPoint = e.Location;
        haveFirstPoint = true;
    }
}

ToolTip trackTip;

private void TrackCoordinates()
{
    trackTip = new ToolTip();
    this.MouseMove += new MouseEventHandler(Form1_MouseMove);
}

void Form1_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
    String tipText = String.Format("({0}, {1})", e.X, e.Y);
    trackTip.Show(tipText, this, e.Location);
}