function getIframeDocument(el) {
    var oIframe = Ext.get('center-iframe').dom;
    var oDoc = oIframe.contentWindow || oIframe.contentDocument;
    if(oDoc.document) {
        oDoc = oDoc.document;
    }
    return oDoc;
}

Simple = function() {
    var northPanel, southPanel, eastPanel, westPanel, centerPanel;
    return {
        init : function() {
           var simpleToolbar = new Ext.Toolbar('center-tb');
           simpleToolbar.addButton({
               text: 'Scroll Bottom', cls: 'x-btn-text-icon scroll-bottom', handler: function(o, e) {
                   var iframeDoc = getIframeDocument('center-iframe');
                   iframeDoc.body.scrollTop = iframeDoc.body.scrollHeight;
               }
           });
           simpleToolbar.addButton({
               text: 'Scroll Top', cls: 'x-btn-text-icon scroll-top', handler: function(o, e) {
                   var iframeDoc = getIframeDocument('center-iframe');
                   iframeDoc.body.scrollTop = 0;
               }
           });
           var mainLayout = new Ext.BorderLayout(document.body, {
                north: { 
                    split: true, initialSize: 50 
                }, 
                south: { 
                    split: true, initialSize: 125, titlebar: true, collapsedTitle: 'Status', collapsible: true 
                }, 
                east: { 
                    split: true, initialSize: 100 
                }, 
                west: { 
                    split: true, initialSize: 100, titlebar: true, collapsible: true
                }, 
                center: { titlebar: true}
            });
            mainLayout.beginUpdate();
            mainLayout.add('north', northPanel = new Ext.ContentPanel('north-div', { 
                fitToFrame: true, closable: false 
            }));
            mainLayout.add('south', southPanel = new Ext.ContentPanel('south-div', { 
                fitToFrame: true, closable: false, title: 'Status'
            }));
            mainLayout.add('east', eastPanel = new Ext.ContentPanel('east-div', { 
                fitToFrame: true, closable: false 
            }));
            mainLayout.add('west', westPanel = new Ext.ContentPanel('west-div', { 
                fitToFrame: true, closable: false, title: 'Navigation'
            }));
            mainLayout.add('center', centerPanel = new Ext.ContentPanel('center-div', { 
                fitToFrame: true, autoScroll: true, resizeEl: 'center-iframe', toolbar: simpleToolbar, title: 'Content'
            })); 
            mainLayout.endUpdate();
            northPanel.setContent('This panel will be used for a header');
            Ext.get('center-iframe').dom.src = 'index.html';
        }
    };
}();
Ext.EventManager.onDocumentReady(Simple.init, Simple, true);