Im using jquery dropdown selectbox from http://www.misfitgeek.com/2011/04/jquery-styled-dropdownlist/
its working fine except i want to change background to 0bg_select.png when clicked and when dropdown is up then the image to previous one. Can any one help

      <!-- aspx -->
                <link href= Styles/Selectbox.css  rel= stylesheet  type= text/css  />
                    <script src= http://ajax.aspnetcdn.com/ajax/jQuery/jquery-1.5.1.js 
                            type= text/javascript  charset= utf-8 ></script>
                    <script type= text/javascript  src= Scripts/jquery.selectbox-0.5.js >
                    </script>
                    <script src= Scripts/PageScript.js  type= text/javascript ></script>
        <asp:DropDownList runat= server  name= Items  id= Items 
                              class= StyledDD  ClientIDMode= Static >
              <asp:ListItem>One</asp:ListItem>
              <asp:ListItem>Two</asp:ListItem>
              <asp:ListItem>Three</asp:ListItem>
              <asp:ListItem>Four</asp:ListItem>
            </asp:DropDownList>

        <!--    jquery function  -->
            $(document).ready(function () {
                $( .StyledDD ).selectbox();
            });

    <!-- CSS --->
    /* Drop down styles*/
    div.selectbox-wrapper {
      position:absolute;
      width:400px;
      background-color:white;
      border:1px solid #ccc;
      margin:0px;
      margin-top:-10px;
      padding:0px;
      text-align:left;
      max-height:200px;
      overflow:auto;
    }

    /*Drop down list styles*/
    div.selectbox-wrapper ul {
      list-style-type:none;
      margin:0px;
      padding:0px;
    }
    /* Selected item in dropdown list*/
    div.selectbox-wrapper ul li.selected {
      background-color: #EAF2FB;
    }
    /*
 * jQuery selectbox plugin
 *
 * Copyright (c) 2007 Sadri Sahraoui (brainfault.com)
 * Licensed under the GPL license and MIT:
 *   http://www.opensource.org/licenses/GPL-license.php
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * The code is inspired from Autocomplete plugin (http://www.dyve.net/jquery/?autocomplete)
 *
 * Revision: $Id$
 * Version: 0.5
 * 
 * Changelog :
 *  Version 0.5 
 *  - separate css style for current selected element and hover element which solve the highlight issue 
 *  Version 0.4
 *  - Fix width when the select is in a hidden div   @Pawel Maziarz
 *  - Add a unique id for generated li to avoid conflict with other selects and empty values @Pawel Maziarz
 */
jQuery.fn.extend({
    selectbox: function(options) {
        return this.each(function() {
            new jQuery.SelectBox(this, options);
        });
    }
});


/* pawel maziarz: work around for ie logging */
if (!window.console) {
    var console = {
        log: function(msg) {
        }
    };
}
/* */

jQuery.SelectBox = function (selectobj, options) {

    var opt = options || {};
    opt.inputClass = opt.inputClass || "selectbox";
    opt.containerClass = opt.containerClass || "selectbox-wrapper";
    opt.hoverClass = opt.hoverClass || "current";
    opt.currentClass = opt.selectedClass || "selected";
    opt.debug = opt.debug || false;

    var elm_id = selectobj.id;
    var active = -1;
    var inFocus = false;
    var hasfocus = 0;
    //jquery object for select element
    var $select = $(selectobj);
    // jquery container object
    var $container = setupContainer(opt);
    //jquery input object 
    var $input = setupInput(opt);
    // hide select and append newly created elements
    $select.hide().before($input).before($container);


    init();

    $input
    .click(function () {
        if (!inFocus) {
            $container.toggle();
        }
    })
    .focus(function () {
        if ($container.not( :visible )) {
            inFocus = true;
            $container.show();
        }
    })
    .keydown(function (event) {
        switch (event.keyCode) {
            case 38: // up
                event.preventDefault();
                moveSelect(-1);
                break;
            case 40: // down
                event.preventDefault();
                moveSelect(1);
                break;
            //case 9:  // tab     
            case 13: // return
                event.preventDefault(); // seems not working in mac !
                $( li.  + opt.hoverClass).trigger( click );
                break;
            case 27: //escape
                hideMe();
                break;
        }
    })
    .blur(function () {
        if ($container.is( :visible ) && hasfocus > 0) {
            if (opt.debug) console.log( container visible and has focus );          
        } else {
            hideMe();
        }
    });


    function hideMe() {
        hasfocus = 0;
        $container.hide();
    }

    function init() {
        $container.append(getSelectOptions($input.attr( id ))).hide();
        var width = $input.css( width );
        $container.width(width);
        $container.attr( padding-left ,  30px );
    }

    function setupContainer(options) {
        var container = document.createElement("div");
        $container = $(container);
        $container.attr( id , elm_id +  _container );
        $container.addClass(options.containerClass);

        return $container;
    }

    function setupInput(options) {
        var input = document.createElement("input");
        var $input = $(input);
        $input.attr("id", elm_id + "_input");
        $input.attr("type", "text");
        $input.addClass(options.inputClass);
        $input.attr("autocomplete", "off");
        $input.attr("readonly", "readonly");
        $input.attr("tabIndex", $select.attr("tabindex")); // "I" capital is important for ie

        return $input;
    }

    function moveSelect(step) {
        var lis = $("li", $container);
        if (!lis) return;

        active += step;

        if (active < 0) {
            active = 0;
        } else if (active >= lis.size()) {
            active = lis.size() - 1;
        }

        lis.removeClass(opt.hoverClass);

        $(lis[active]).addClass(opt.hoverClass);
    }

    function setCurrent() {
        var li = $("li." + opt.currentClass, $container).get(0);
        var ar = (   + li.id).split( _ );
        var el = ar[ar.length - 1];
        $select.val(el);
        $input.val($(li).html());
        return true;
    }

    // select value
    function getCurrentSelected() {
        return $select.val();
    }

    // input value
    function getCurrentValue() {
        return $input.val();
    }

    function getSelectOptions(parentid) {
        var select_options = new Array();
        var ul = document.createElement( ul );
        $select.children( option ).each(function () {
            var li = document.createElement( li );
            li.setAttribute( id , parentid +  _  + $(this).val());
            li.innerHTML = $(this).html();
            if ($(this).is( :selected )) {
                $input.val($(this).html());
                $(li).addClass(opt.currentClass);
            }
            ul.appendChild(li);
            $(li)
            .mouseover(function (event) {
                hasfocus = 1;
                if (opt.debug) console.log( over on :   + this.id);
                jQuery(event.target, $container).addClass(opt.hoverClass);
            })
            .mouseout(function (event) {
                hasfocus = -1;
                if (opt.debug) console.log( out on :   + this.id);
                jQuery(event.target, $container).removeClass(opt.hoverClass);
            })
            .click(function (event) {
                var fl = $( li.  + opt.hoverClass, $container).get(0);
                if (opt.debug) console.log( click on :  + this.id);
                $( li.  + opt.currentClass).removeClass(opt.currentClass);
                $(this).addClass(opt.currentClass);
                setCurrent();
                hideMe();
            });
        });
        return ul;
    }

};

    /* Hover state for dropdown list */
    div.selectbox-wrapper ul li.current {
      background-color: #CDD8E4;
    }

    /* Drop down list items style*/
    div.selectbox-wrapper ul li {
      list-style-type:none;
      display:block;
      margin:0;
      padding:2px;
      cursor:pointer;
    }

    /* Look and feel of select box */
    .selectbox
    {
      margin: 0px 5px 10px 0px;
      padding-left:2px;
      font-family:Verdana, Geneva, Arial, Helvetica, sans-serif;
      font-size:1em;/* Resize Font*/
      width : 190px; /* Resize Width */
      display : block;
      text-align:left;
      background: url( ../images/bg_select.png ) right;
      cursor: pointer;
      border:1px solid #D1E4F6;
      color:#333;
    }