I find a bug

[javasmile]

    <div id="son-dialog" style="display: none;">son</div>
    <div id="main-dialog" style="display: none;">main</div> 
    <script>
        $(function() {
            var sonDialog = $('#son-dialog').dialog({
                autoOpen : false,
                modal : true
            });
            var mainDialog= $("#main-dialog").dialog({
                autoOpen : true,
                modal : true,
                buttons : {
                    'click' : function() {
                        sonDialog.dialog('open');
                    }
                }
            });
        });
    </script>

Main dialog can not be overlaid by Son dialog.
Reason:
L1306: .ui-dialog {z-index: 1050;}
1050 -> 100 as ui-front
ok