Air viewport and panel

[Bouki]

Hi
I want to have a panel fitting my viewport.
Previously I had :

var window = new Ext.air.Window({
    //...
    items:[panel]
});

Now I want to do this :

var window = new Ext.air.Window({
    //...
    items:[]
});
window.on('complete', function () {
    viewport = window.getViewport();
}, this);
//and later
    viewport.removeAll();
    viewport.add(panel);

However the second code doesn't work : the panel has a limited height or 0 height (depending if it contains extjs components or html)