/// <summary>
/// Raises the <see cref="E:System.Windows.Forms.Control.MouseDown"></see> event.
/// </summary>
/// <param name="e">A <see cref="T:System.Windows.Forms.MouseEventArgs"></see> that contains the event data.</param>
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
columns.MouseDown(e);
Focus();
}