How to make an asp dropdown list item unselectable

Question

I have written following code to display drop down list :

<asp:DropDownList AutoPostBack="True" ID="ddlCities" runat="server" class="form-control input-sm" placeholder="" TabIndex="5">
       <asp:ListItem>Select City</asp:ListItem>
       <asp:ListItem value="3">Ahmedabad (All) ---------------</asp:ListItem>
       <asp:ListItem value="3_3004">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad East</asp:ListItem>
       <asp:ListItem value="3_3005">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad West</asp:ListItem>
       <asp:ListItem value="3_3006">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad-Bopal and Surroundings</asp:ListItem>
       <asp:ListItem value="3_3007">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad-Gandhinagar</asp:ListItem>
       <asp:ListItem value="3_3008">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad-Sabarmati and Surroundings</asp:ListItem>
       <asp:ListItem value="3_3009">&nbsp;&nbsp;&nbsp;&nbsp;Ahmedabad-SG Highway and Surroundings</asp:ListItem>
</asp:DropDownList>

I want to make following item inside dropdown unselectable :

<asp:ListItem value="3">Ahmedabad (All) ---------------</asp:ListItem>

Note : I CAN'T USE OPTGROUP!!!!

and i don't want to hide it. it will be shown in dropdown, but user can't select this item.

I have tried adding 'disabled' attribute, but it hides that item.

i have also tried :

ddlCities.Items[1].Attributes.Add("Style", "cursor:not-allowed");

It doesn't allow cursor, but still user can select this item, is there any other way to make this particular item unselectable??

Answer 1

Even though you said that disabled attribute hides the element, you are wrong. Disabled attribute is exactly what you should use for this:

    <asp:DropDownList ID="DropDownList1" runat="server">
        <asp:ListItem Value="1">First</asp:ListItem>
        <asp:ListItem Value="2" disabled="disabled">Second</asp:ListItem>
        <asp:ListItem Value="3">First</asp:ListItem>
    </asp:DropDownList>

Result:

Answer 2

I think you're looking for something like this . Please see if it can help you.

[Update] just looked back to your post and understand you cannot use OPTGROUP. May i know the reason? as your requirement needs this option.