gistfile1.txt

mywin = Ext.create('Ext.window.Window', {
    title: 'Hello',
    height: 400,
    width: 400,
    layout: {
        type: 'table',
        columns: 3
    },
    items: [
        {
            xtype: 'textfield',
            colspan: 3
        },
        {
            xtype: 'button',
            text: '7',
            listeners: {
                'click': function() {
                    var oldValue = mywin.down('textfield').getValue();
                    mywin.down('textfield').setValue(oldValue + '7');
                }
            }
        },
        {
            xtype: 'button',
            text: '8'
        },
        {
            xtype: 'button',
            text: '9'
        },
        {
            xtype: 'button',
            text: '4'
        },
        {
            xtype: 'button',
            text: '5'
        },
        {
            xtype: 'button',
            text: '6'
        },
        {
            xtype: 'button',
            text: '1'
        },
        {
            xtype: 'button',
            text: '2'
        },
        {
            xtype: 'button',
            text: '3'
        },
        {
            xtype: 'button',
            text: '0'
        },
        {
            xtype: 'button',
            text: 'clear',
            colspan: 2
        }
    ]
});

mywin.show();