I've got a typical form where I want the user to enter the password and a confirmation of the password and i want them to be validated to be the same. How can I do that with an SA project?

Code:
 items: [
                {
                    xtype: 'textfield',
                    itemId: 'username',
                    inputId: 'username',
                    fieldLabel: 'Username',
                    allowBlank: false
                },
                {
                    xtype: 'textfield',
                    itemId: 'password',
                    inputId: 'password',
                    inputType: 'password',
                    fieldLabel: 'Password',
                    allowBlank: false
                },
                {
                    xtype: 'textfield',
                    itemId: 'passwordConfirm',
                    inputId: 'passwordConfirm',
                    inputType: 'password',
                    fieldLabel: 'Confirm Password'
                },
                {
                    xtype: 'textfield',
                    itemId: 'email',
                    inputId: 'email',
                    fieldLabel: 'Email Address',
                    allowBlank: false,
                    vtype: 'email'
                }
            ]