I'm wondering if someone might help me out...

I want the button in a west panel(anchor layout and resize-able) in a viewport to hide the overflowed text so the button fits the panel, not expand the button beyond the panels' split.
Code:
     new Ext.Viewport({
        layout: 'border',
        items: [{
            region: 'west',
            layout: 'anchor',
            width: 200,
            collapsible: false,
            split: true,
            useArrows: false,
            items: new Ext.Button({
                text: 'asd asd asd asd asd asd asd asd asd asd asd asd', 
                anchor: '100%'                    
            })
           },{
            region: 'center'
        }]
     });
button-viewport-west.jpg