Set minimum dialog dimensions?

Set minimum dialog dimensions?


Is it possible to limit the smallest a dialog can become?
I have an <iframe> and a pair of buttons in a dialog. When the Dialog
reaches a certian size the iframe (with a pdf in it) it overlays the
buttons. This, unfortunately is a problem.
$(document).ready(function() {
    $('#example').dialog({
            autoOpen: false,
            modal: true,
            overlay: {
                opacity: 0.5,
                background: "black"},
            buttons: {
                "Ok": function() {
                    alert("Ok");
                },
                "Cancel": function() {
                    $(this).dialog("close");
                }
            },
            height:600,
            width:700,
            open: function() {
                $('#example iframe').height($(this).height()-70);
                $('#example iframe').width($(this).width()-20); },
            resize: function() { $('iframe').hide(); },
            resizeStop: function() { $('iframe').show();
                $('#example iframe').height($(this).height()-70);
                $('#example iframe').width($(this).width()-40);             }
    });
    $('#example').dialog("open");
});
        </script>
    </head>
    <body>
<div id="example">
<iframe src="/mypdf.pdf" border="0" /></div>