private void ModelChk_MouseMove(object sender, MouseEventArgs e)
 {
     if (ttIndex != ModelChk.IndexFromPoint(e.Location))
     {
         GetModelToolTip();
     }
 }
        private void GetModelToolTip()
        {
            //foreach (var chk in ModelChk.Items)
            //{
            //    chk.Attributes.Add("title", "salam");
            //}

            ttIndex = ModelChk.IndexFromPoint(ModelChk.PointToClient(MousePosition));
            if (ttIndex > -1)
            {
                System.Drawing.Point p = PointToClient(MousePosition);
                toolTip1.ToolTipTitle = ModelChk.Items[ttIndex].ToString();
                toolTip1.SetToolTip(ModelChk, frmParent.ModelsTip[ttIndex].ToString());
            }
        }