If you find any html page in gwt, you will find two entries which is common to all html page of gwt.
That is below.
<script type="text/javascript" language="javascript" src="{modulename}/{modulename}.nocache.js"></script>
<body>
<iframe src="javascript:''" id="__gwt_historyFrame" tabIndex='-1' style="position:absolute;width:0;height:0;border:0"></iframe>
</body>
It loads module.cache.js
into iframe
.
So In short gwt work on one page only. it is single page application.