Extended Widget onLoad Event

Summary

how to fire an event on selectInput page load time

Content

I have a Widget that extends the SelectionInput standard widget.

In the constructor, there is a listener for a CHANGE event, which invokes the _selection() funcion.

  overrides: {

        /**

         * Overrides RightNow.Widgets.SelectionInput#constructor.

         */

        constructor: function() {

            // Call into parent's constructor       

            this.parent();    

            this.on('change', this._selection, this);

So, I need the same of functionality for the onLoad event.
I've tried the following line in the constructor (and created the _load function as well), but it didn't work

 this.on('load', this._load, this);

Is there a way to achieve this requirement?