You can hook client-side events that fire for various dropdownlist events, such as selection, dropdown hide/show, etc. This is achieved through the collection of the JQDropDownList class. Each event is a string pointing to a javascript function that will execute when the event is fired. Each function typically receives two parameters - the item causing the event and the event argument of the browser (client-side event). Some events like Select, etc can be cancelled by returning false from the event handler. Please, refer to the View tab for additional details.
@using Trirand.Web.Mvc

<!DOCTYPE html>
<html lang="en-us">
<head>
    <meta charset="utf-8">
    <title>jqDropDownList for ASP.NET MVC - Client-Side Events</title>    
    <!-- The jQuery UI theme that will be used by jqDropDownList -->
    <script src="~/Scripts/jquery-3.0.0.min.js" type="text/javascript"></script>
    <!-- The jqTreeView client-side javascript -->
    <script src="~/Scripts/trirand/jquery.jqDropDownList.min.js" type="text/javascript"></script>
    <!-- The jqTemplating javascript -->
    <script src="~/Scripts/trirand/jquery.jqTemplating.min.js" type="text/javascript"></script>
    <!-- The jQuery UI theme that will be used by the grid. -->
    <link rel="stylesheet" type="text/css" href="http://code.jquery.com/ui/1.11.4/themes/redmond/jquery-ui.css" />
    <!-- The jQuery UI theme extension jqTreeView needs -->
    <link rel="stylesheet" type="text/css" href="~/Content/themes/ui.jqDropDownList.css" />
</head>
<body>    
    <table cellpadding="10" cellspacing="10"> 
        <tr>
            <td valign="top">
                @(Html.Trirand().JQDropDownList(
                new JQDropDownList
                {
                    Height = 200,
                    Width = 150,
                    Items = new List<JQListItem>
                    {
                        new JQListItem { 
                            Text = "One", 
                            Value = "One",
                            ImageUrl = "/content/images/folder.png"
                        },
                        new JQListItem 
                        { 
                            Text = "Two", 
                            Value = "Two",
                            ImageUrl = "/content/images/folder-open.png"
                        },
                        new JQListItem 
                        { 
                            Text = "Three", 
                            Value = "Three",
                            ImageUrl = "/content/images/document.png"
                        }
                    },
                    ClientSideEvents = new DropDownListClientSideEvents
                    {
                        Show = "handleShow",
                        Hide = "handleHide",
                        MouseOver = "handleMouseOver",
                        MouseOut = "handleMouseOut",
                        Select = "handleSelect",
                        Initialized = "handleInitialized",
                        KeyDown = "handleKeyDown"
                    }
                }, "dropdownlist"))
            </td>
            <td valign="top" style="width:300px; height: 300px;">                
                <div id="eventLog" style="height:300px; overflow:auto; font-size:110%; font-family:Tahoma" />
            </td>
        </tr>
    </table>
    
    <script type="text/javascript">
    
    function handleInitialized(dropDown) {
        write("DropDownList initialized.");
    }
    
    function handleKeyDown(dropDown, events) {
        write(events.keyCode + " is the keyCode of the key pressed.");
    }
    
    function handleShow() {        
        write("DropDown shown.");
    }
    
    function handleHide() {                
        write("DropDown hidden.");
    }
    
    function handleMouseOut(item, event) {
        var dropDown = $("#dropdownlist").getDropDownListInstance();
        var itemOptions = dropDown.getItemOptions(item);
        
        writeLine(itemOptions.text, "<b>MouseOut</b> fired");
    }
    
    function handleMouseOver(item, event) {
        var dropDown = $("#dropdownlist").getDropDownListInstance();
        var itemOptions = dropDown.getItemOptions(item);
        
        writeLine(itemOptions.text, "<b>MouseOver</b> fired");
    }
    
    function handleSelect(item, event) {
        var dropDown = $("#dropdownlist").getDropDownListInstance();
        var itemOptions = dropDown.getItemOptions(item);             
        
        if (itemOptions.text == "Two") {
            writeLine(itemOptions.text," : <b>cannot be selected</b>");
            return false;
        }
        
        writeLine(itemOptions.text, " : <b>Select</b> fired");
    }
    
    function writeLine(itemText, message) {
        var currentText = $("#eventLog").html();
        $("#eventLog").html(message + " for item <b>" + itemText + "</b><br>" + currentText);
    }
    
    function write(message) {
        var currentText = $("#eventLog").html();
        $("#eventLog").html("<b>" + message + "</b><br>" + currentText);
    }
    
    </script>
            
    
    <br /><br /><br />
    <br /><br /><br />
    <div>
          
    </div>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Trirand.Web.Mvc;

namespace MVCDemo.Controllers.DropDownList
{
    public partial class DropDownListController : Controller
    {
        public ActionResult ClientEvents()
        {
            return View();
        }         
    }
}
Switch theme:


Theming is based on the very popular jQuery ThemeRoller standard. This is the same theming mechanism used by jQuery UI and is now a de-facto standard for jQuery based components. The benefits of using ThemeRoller are huge. We can offer a big set of ready to use themes created by professional designers, including Windows-like themes (Redmond), Apple-like theme (Cupertino), etc. In addition to that any jQuery UI controls on the same page will pick the same theme.

Last, but not least, you can always roll your own ThemeRoller theme, using the superb Theme Editor

To use a theme, simply reference 2 Css files in your Html <head> section - the ThemeRoller theme you wish to use, and the jqGrid own ThemeRoller Css file. For example (Redmond theme):

<link rel="stylesheet" type="text/css" media="screen" href="/themes/redmond/jquery-ui-1.8.2.custom.css" />
<link rel="stylesheet" type="text/css" media="screen" href="/themes/ui.jqgrid.css" />