Hello together

Can somebody help me to make the following code working in Ext JS 4.1 RC2? I copied the code from here http://www.sencha.com/forum/showthre...panel&p=269519.

Code:
var grid = new Ext.grid.GridPanel({
	store: new Ext.data.SimpleStore({
		fields: ['a', 'b', 'c'],
		data: [
			[1, 2, 3],
			[2, 3, 4],
			[3, 4, 5]
		]
	}),
	columns: [
		{header: 'A', dataIndex: 'a', width: 1},
		{header: 'B', dataIndex: 'b', width: 1},
		{header: 'C', dataIndex: 'c', width: 1}
	],
	cellPadding: 8,
	autoSizeColumn: function(colIndex) {
		var w = this.view.getHeaderCell(colIndex).firstChild.scrollWidth;
		for (var r = 0, len = this.store.getCount(); r < len; r++) {
			w = Math.max(w, this.view.getCell(r, colIndex).firstChild.scrollWidth);
		}
		w += this.cellPadding;
		this.colModel.setColumnWidth(colIndex, w);
		return w;
	},
	viewConfig: {
		afterRender: function(){
			this.constructor.prototype.afterRender.apply(this, arguments);
			this.grid.autoSizeColumn(0);
			this.grid.autoSizeColumn(1);
			this.grid.autoSizeColumn(2);
		}
	}
});
new Ext.Viewport({
	layout: 'fit',
	items: grid
});
Thanks for your support!

Kind regards
extjser12