如何在extjs中的两个视图之间共享相同的viewModel？

Ext.application({
    name: 'MyApp',
    launch: function() {
        Ext.define('MyApp.view.MyViewModel', {
            extend: 'Ext.app.ViewModel',
            alias: 'viewmodel.myviewmodel'
        });

        Ext.create('MyApp.view.MyView1', {
            viewModel: 'myviewmodel'
        });

        Ext.create('MyApp.view.MyView2', {
            viewModel: 'myviewmodel'
        });
    }
});

Ext.define('MyApp.view.MyView1', {
    extend: 'Ext.panel.Panel',
    viewModel: 'myviewmodel',
    //...
});

Ext.define('MyApp.view.MyView2', {
    extend: 'Ext.panel.Panel',
    viewModel: 'myviewmodel',
    //...
});