//----------------------------------------------------
        /// <summary>
        /// BDataGridView cell enters edit mode 時発生します
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        //----------------------------------------------------
        private void bDgvToti_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            ComboBox cmb = e.Control as ComboBox;
            if (cmb != null)
            {
                cmb.DropDown -= new EventHandler(bDgvCmb_DropDown);
                cmb.DropDown += new EventHandler(bDgvCmb_DropDown);
            }
        }

        //----------------------------------------------------
        /// <summary>
        /// auto-size the DataGridViewComboBoxColumns's DropDownWidth
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        //----------------------------------------------------
        private void bDgvCmb_DropDown(object sender,EventArgs e)
        {
            ComboBox cmb = sender as ComboBox;
            int width = cmb.DropDownWidth;
            Graphics g = cmb.CreateGraphics();
            Font font = cmb.Font;
            int vertScrollBarWidth = 0;
            if (cmb.Items.Count > cmb.MaxDropDownItems)
                vertScrollBarWidth = SystemInformation.VerticalScrollBarWidth;

            int maxWidth;
            foreach (DataRowView drv in cmb.Items)
            {
                string s = drv[0].ToString();
                maxWidth = (int)g.MeasureString(s, font).Width + vertScrollBarWidth;
                if (width < maxWidth)
                    width = maxWidth;
            }

            DataGridViewComboBoxColumn c =
                this.bDgvToti.Columns[bDgvToti.CurrentCell.ColumnIndex] as DataGridViewComboBoxColumn;
            if (c != null)
                c.DropDownWidth = width;
        }