protected override void OnLostFocus(EventArgs e)
{
// We lost the focus
_manualFocus = false;
// Remove tracking of any item
_trackItem = SwitchTrackingItem(_trackItem, -1);
// No need to remember old focus anymore
_oldFocus = IntPtr.Zero;
// When we lose focus we sometimes miss the WM_MOUSELEAVE message
_mouseOver = false;
base.OnLostFocus(e);
}