As written on the API docs: An Action Provider Widget is a widget that has declared several actions by using its 'public static function actions()'. After, a Controller can easily import all its declared actions on its 'public function actions()'.
In case of a multilingual application, one might consider it a reasonable approach to store the preferred language of the user in a session variable, and after that, every time a page is requested, to check this session variable and render the page in the indicated language.
This tutorial shows a Yii-way of doing this.
We implement an event handler for the onBeginRequest event; as the name of the event suggests, this event handler will be called at the beginning of each request, so its a good place to check whether a language is provided (via post, session or cookie) and set the application language accordingly.
We also implement a simple Language-Selector Widget, which can render the language options as ajax-links or as a drop-down list.
I have been requested to provide a tutorial on how to use the file upload feature of the TbRedactor widget, and even though I am no longer supporting the library due that the work belongs to Clevertech, I feel that I owe that to the Yii developers. So, here is the tutorial.
To extend the functionality of you web application relative to your requirements you are supposed to use existing yii core libraries or use external libraries. There are some steps to ensure security, uniqueness, modularity, performance and to avoid rework in future.
In Yii 2.0, the yii widgets that use Twitter Bootstrap CSS & JS directly, are part of the yii2-bootstrap extension, starting with yii/bootstrap namespace. For customizing bootstrap extension specific widget assets, you could configure your own assets (CSS/JS) using the new Yii Asset Manager in your Yii Config file. Something like: