My app comes up blank

Hi,

My app comes up blank. Thanks for helping.

Here is my application.js:

Code:

Ext.application({
    name: "GiipIq",
    appFolder: "app",
    autoCreateViewport: true,
    //controllers: ['Problems']
});

Here is my Viewport:

Code:

Ext.define("GiipIq.view.Viewport", {
    extend: "Ext.container.Viewport",
    layout: "fit",
        requires: ["GiipIq.view.Problem"],
        
        initComponent: function() {
                this.items = [{
                        xtype: "problemwindow"
                }];
                this.callParent();
        }
});

Here is my view:

Code:

Ext.define("GiipIq.view.Problem", {
    extend: "Ext.window.Window",
    alias: "widget.problemwindow",
        title: "Problems to be run",
        closable: false,
        layout: "border",

        getEastPanel: function() {
                return {
                        region: "west",
                        title: "Available Problems",
                        width: 200,
                        split: true,
                        collapsible: true,
                        floatable: false,
                        xtype: "panel",
                        rootVisible: false,
                        //store: store
                };
        },

        getCentralPanel: function() {
                return {
                };
        },

    initComponent: function () {
                this.items = [
                        this.getEastPanel(),
                        //this.getCentralPanel()
                ];
                this.callParent(arguments);
    }
});