Class YAHOO.ext.LayoutDialog

if(!dialog){
    dialog = new YAHOO.ext.LayoutDialog("download-dlg", { 
            modal: true,
            width:600,
            height:450,
            shadow:true,
            minWidth:500,
            minHeight:350,
            autoTabs:true,
            proxyDrag:true,
            // layout config merges with the dialog config
            center:{
                tabPosition: 'top',
                alwaysShowTabs: true
            }
    });
    dialog.addKeyListener(27, dialog.hide, dialog);
    dialog.setDefaultButton(dialog.addButton('Close', dialog.hide, dialog));
    dialog.addButton('Build It!', this.getDownload, this);
    
    // we can even add nested layouts
    var innerLayout = new YAHOO.ext.BorderLayout('dl-inner', {
        east: {
            initialSize: 200,
            autoScroll:true,
            split:true
        },
        center: {
            autoScroll:true
        }
    });
    innerLayout.beginUpdate();
    innerLayout.add('east', new YAHOO.ext.ContentPanel('dl-details'));
    innerLayout.add('center', new YAHOO.ext.ContentPanel('selection-panel'));
    innerLayout.endUpdate(true);
    
    // when doing updates to the top level layout in a dialog, you need to 
    // use dialog.beginUpdate()/endUpdate() instead of layout.beginUpdate()/endUpdate()
    var layout = dialog.getLayout();
    dialog.beginUpdate();
    layout.add('center', new YAHOO.ext.ContentPanel('standard-panel', 
                        {title: 'Download the Source', fitToFrame:true}));
    layout.add('center', new YAHOO.ext.NestedLayoutPanel(innerLayout, 
               {title: 'Build your own yui-ext.js'}));
    layout.getRegion('center').showPanel(sp);
    dialog.endUpdate();