C#

private void button1_Click(object sender, EventArgs e)
{
    listBox1.Visible = true;
    listBox1.Focus();
}

private void listBox1_Leave(object sender, EventArgs e)
{
    listBox1.Visible = false;
}

private void WindowsApplication1_Click(object sender, EventArgs e)
{
    listBox1.Visible = false;
}

bobsugar222 wrote:

private void WindowsApplication1_Click(object sender, EventArgs e)

//Show the listbox
private void button1_Click(object sender, System.EventArgs e)
{
	this.listBox1.Visible = true;
}

// hide the listbox if it looses focus
private void listBox1_Leave(object sender, System.EventArgs e)
{
	this.listBox1.Visible = false;
}

//event handler for Form.MouseDown (and later for each control)
private void Control_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
	if(sender != this.listBox1)
		this.listBox1.Visible=false;
}

protected override void OnControlAdded(ControlEventArgs e)
{
	e.Control.MouseDown += new MouseEventHandler(Control_MouseDown);
	base.OnControlAdded (e);
}