static public string DropDownListSelectChangeConfirmScript(string dropDownListId,string message)
{
    string script = " <script> \n"
        +" var fooIndex; \n"
        +" function saveIndexes() \n"
        +" { \n"
        +"    fooIndex = document.all['"+dropDownListId+"'].selectedIndex; \n"
        +" } \n"
        +" function resetIndexes() \n"
        +" { \n"
        +"    document.all['"+dropDownListId+"'].selectedIndex = fooIndex; \n"
        +" } \n"
        +" function areYouSure() \n"
        +" { \n"
        +"    if( !confirm('"+message+"')) \n"
        +"    { \n"
        +"      resetIndexes(); \n"
        +"      return false; \n"
        +"    } \n"
        +"    else \n"
        +"    { \n"
        +"      document.all['"+dropDownListId+"'].detachEvent('onchange', areYouSure); \n"
        +"      return true; \n"
        +"    } \n"
        +" } \n"
        +" saveIndexes(); \n"
        +" document.all['"+dropDownListId+"'].attachEvent('onchange', areYouSure); "
        +"</script>\n";
    return script;
}
private void RegisterClientScript(string dropDownListClientId)
{
    string script = DropDownListSelectChangeConfirmScript(
        dropDownListClientId,
        "Are you sure?"
        );
    if(!IsStartupScriptRegistered("startup"))
    {
        RegisterStartupScript("startup",script);
    }

}