The source code

    Ext.onReady(function() {
        var form = new Ext.form.FormPanel({
            baseCls: 'x-plain',
            layout:'absolute',
            url:'save-form.php',
            defaultType: 'textfield',

            items: [{
                x: 0,
                y: 5,
                xtype:'label',
                text: 'Send To:'
            },{
                x: 60,
                y: 0,
                name: 'to',
                anchor:'100%'  // anchor width by percentage
            },{
                x: 0,
                y: 35,
                xtype:'label',
                text: 'Subject:'
            },{
                x: 60,
                y: 30,
                name: 'subject',
                anchor: '100%'  // anchor width by percentage
            },{
                x:0,
                y: 60,
                xtype: 'textarea',
                name: 'msg',
                anchor: '100% 100%'  // anchor width and height
            }]
        });

        var window = new Ext.Window({
            title: 'Resize Me',
            width: 500,
            height:300,
            minWidth: 300,
            minHeight: 200,
            layout: 'fit',
            plain:true,
            bodyStyle:'padding:5px;',
            buttonAlign:'center',
            items: form,

            buttons: [{
                text: 'Send'
            },{
                text: 'Cancel'
            }]
        });

        window.show();
    });