TextBox蓋在DropDownList上面.實現可刪除的DropDownList

           this.ddOperatorName.Attributes.Add("onChange", "javascript:document.getElementById('ctl00_MainContentPlace_txtOperatorName').value=document.getElementById('ctl00_MainContentPlace_ddOperatorName').options[document.getElementById('ctl00_MainContentPlace_ddOperatorName').selectedIndex].value;");

                <span style="position:absolute;border:1pt solid #c1c1c1;overflow:hidden;width:190px;clip:rect(-1px 190px 190px 175px);">
                <asp:DropDownList ID="ddReceiptType" runat="server" CssClass="DropDownListStyle"
                    DataSourceID="ObjectDataSource2" DataTextField="AttributeName" OnDataBound="ddReceiptType_DataBound" Width="190px">
                </asp:DropDownList>
                </span>
                <span style="position:absolute;border-top:1pt solid #c1c1c1;border-left:1pt solid #c1c1c1;border-bottom:1pt solid #c1c1c1;width:175px;">
                    <asp:TextBox ID="txtReceiptType" Width="175px" runat="server"/>
                </span>