There are several, in fact take a look at the source for the API & Examples documentation section. That's how I implemented mine. Just a note though make sure you put your script includes for the JS files after the loading div. That little oversight made my life hell for a bit.
Here are some snippets for you to chew on.
CSS Additions - Add to your custom CSS file you include with the page you want the "loading..." msg displayed on.
.loading-indicator {
font-size:8pt;
background-image:url('../images/default/grid/loading.gif');
background-repeat: no-repeat;
background-position:top left;
padding-left:20px;
height:18px;
text-align:left;
}
#loading{
position:absolute;
left:45%;
top:40%;
border:1px solid #5C5C5C;
padding:2px;
background:#eeeeee;
width:250px;
text-align:center;
z-index:20001;
}
#loading .loading-indicator{
border:1px solid #aaaaaa;
background:white;
color:#000000;
font:bold 13px tahoma,arial,helvetica;
padding:10px;
margin:0;
}
HTML Additions - Add these DIVS right below the body tag and above the JS includes
<body scroll="no">
<div id="loading-mask" style="width:100%;height:100%;background:#999999;position:absolute;z-index:20000;left:0;top:0;"> </div>
<div id="loading">
<div class="loading-indicator"><img src="images/default/grid/loading.gif" style="width:16px;height:16px;" align="absmiddle"> Loading Service Dogs of GA...</div>
</div>
<script type="text/javascript" src="includes/yui-utilities.js"></script>
<script type="text/javascript" src="includes/ext-yui-adapter.js"></script>
<script type="text/javascript" src="includes/ext-all.js"></script>
<script type="text/javascript" src="includes/homepage.js"></script>
JS Additions - Add this code snippet to the JS file you will be using to load the EXT stuff for your page
var loading = Ext.get('loading');
var mask = Ext.get('loading-mask');
mask.setOpacity(.8);
mask.shift({
xy:loading.getXY(),
width:loading.getWidth(),
height:loading.getHeight(),
remove:true,
duration:1,
opacity:.3,
easing:'bounceOut',
callback : function(){
loading.fadeOut({duration:.2,remove:true});
}
});
Hope that helps. There are plenty of other examples on the forum you just have to use the search function.
Tim