Nothing real special. The AJAX loading icon can be changed using the Javascript variable ajax_load_icon in header.tpl.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html>
<head>
<title>{PAGE_NAME} • {SITE_NAME}</title>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<link rel="stylesheet" type="text/css" href="{SCRIPTPATH}/includes/clientside/css/enano-shared.css" />
<link id="mdgCss" rel="stylesheet" type="text/css" href="{SCRIPTPATH}/themes/{THEME_ID}/css/{STYLE_ID}.css" />
{JS_DYNAMIC_VARS}
<script type="text/javascript" src="{SCRIPTPATH}/themes/admin/js/menu.js"></script>
<script type="text/javascript" src="{SCRIPTPATH}/includes/clientside/static/enano-lib-basic.js"></script>
{ADDITIONAL_HEADERS}
</head>
<body>
<div id="header">
<div class="sitename">{SITE_NAME}</div>
<div class="menulink"><a href="#" onclick="adminOpenMenu('sidebar', this); return false;">expand menu</a></div>
[ <a href="{SCRIPTPATH}/{ADMIN_SID_AUTO}">Main page »</a> ]
</div>
<div class="menu_nojs" id="pagebar_main">
<div class="label">Page tools</div>
{TOOLBAR}
<ul>
{TOOLBAR_EXTRAS}
</ul>
<span class="menuclear"> </span>
</div>
<div id="sidebar">
{SIDEBAR_LEFT}
{SIDEBAR_RIGHT}
</div>
<table border="0" cellspacing="0" cellpadding="0" id="wrapper">
<tr>
<td class="top-left"></td><td class="top"> </td><td class="top-right"></td>
</tr>
<tr>
<td class="left"></td>
<td class="main">
<div style="float: right;">
<img alt=" " src="{SCRIPTPATH}/images/spacer.gif" id="ajaxloadicon" />
</div>
<h2 class="pagename">{PAGE_NAME}</h2>
<div id="ajaxEditContainer">