private void lv1_MouseMove(object sender, MouseEventArgs e)
{
ListViewItem item = lv1.GetItemAt(e.X, e.Y);
if (item != oldItem)
{
oldItem = item;
if (item != null)
{
toolTip1.SetToolTip(lv1, item.Text);
//lv1.Invalidate();
}
else
toolTip1.RemoveAll();
}
}