Cloning filefiled in change function

Cloning filefiled in change function

I have a form include a filefield like;

Is possible? The filefile can clone (with file attached) in change
function like ( if possible, that can change some attribute like
textfield,..?)

Here is my filefile http://jsfiddle.net/23tjk/
items: [{
xtype: 'filefield',
name: 'file',
fieldLabel: 'Upload',
labelWidth: 50,
msgTarget: 'side',
allowBlank: false,
anchor: '100%',
listeners:{
'change': function(f, value){
form.add([f]); // nothing run
}
}
}],