How to render responsive a Ext.form.TextArea - extjs

Question

I need some help about a form with a textarea field.
My problem.
I have a simple Ext.window in which I have put an Ext.FormPanel. In this Ext.FormPanel I have put an Ext.form.FieldSet in which I have put some fields. One of these field is a textarea (Ext.form.TextArea),
Now, my objective is to render responsive this textarea when I resize the Ext.window.
It is possible to obtain this behavior?
This is my current code:
Window in which reside the Ext.FormPanel
var win = new Ext.Window({
id:'winTest',
layout:'fit',
modal:true,
title:'Title',
width:590,
height:300,
closeAction:'close',
plain: true,
autoScroll: true,
items:[form],
listeners: {
'beforeclose': function (p) {
}
}
});
Ext.FormPanel in which reside the Ext.form.FieldSet
var form = new Ext.FormPanel({
id:'FormTest',
layout : 'form',
width:510,
labelAlign: 'right',
labelWidth: 120,
autoScroll:true,
bodyStyle:'padding:2px;background-color:#E9EFF8;',
monitorValid:true,
waitMsgTarget: true,
border: true,
bodyBorder: true,
trackResetOnLoad:true,
items: [fieldset]
});
Fieldset in which I have put some fileds
var fieldset = Ext.form.FieldSet({
id:'fsTest',
autoHeight: true,
defaultType: 'textfield',
items:[.....,textarea]
//boxMaxWidth:450
//border:true
})
Textarea putted in the fieldset (to shorted, I have reported only the textarea)
var textarea = new Ext.form.TextArea({
id:'textareaTest',
name:'TextArea',
fieldLabel:'Insert',
hidden:false,
width:310,
height:60,
maxLength:500,
allowBlank: true
});
Thanks for any precious help.
Lorenzo.

Answer 1

It should be like this:-
var win = new Ext.Window({
id: 'winTest',
layout: 'vbox',
modal: true,
title: 'Title',
width: 590,
height: 300,
closeAction: 'close',
plain: true,
autoScroll: true,
items: [{
xtype: 'form',
id: 'FormTest',
flex: 1,
layout: 'vbox',
width: 510,
labelAlign: 'right',
labelWidth: 120,
autoScroll: true,
bodyStyle: 'padding:2px;background-color:#E9EFF8;',
monitorValid: true,
waitMsgTarget: true,
border: true,
bodyBorder: true,
trackResetOnLoad: true,
items: [{
xtype: 'fieldset',
id: 'fsTest',
//autoHeight: true,
flex: 1,
layout: 'vbox',
//defaultType: 'textfield',
items: [{
xtype: 'textarea',
flex: 1,
id: 'textareaTest',
name: 'TextArea',
fieldLabel: 'Insert',
hidden: false,
width: 310,
//height: 60,
maxLength: 500,
allowBlank: true
}]
//boxMaxWidth:450
//border:true
}]
}]
}).show();
Please have a look at this example