You have that, when a product is on development they can change its API anytime. This change is quite important though, its related on how to set the events of your form, for example, the useful beforeSubmit.
When i had created this functionality then i found some difficulties and not got much idea from wiki and forums. so, i think this will be useful for newbie users and save time of other developers when create related functionality.
I refer Collecting Tabular Input tutorial but not got clear idea for create/update.
In this mini howto I would like to show how to add a required captcha field in the login form, after a defined number of unsuccessfull attempts.
To do this, I will use the blog demo that you have in default Yii download package (path/to/yii/demos/blog).