Can some one provide details about how to make the custom widget to render 100% height of device. Setting width property to 0 is taking 100% width with some padding. Can this padding be removed?
These are problems that can be solved with CSS:
For the height problem, read up on 100% height here.
For handling padding, you need to find out where the padding is being applied, and then remove it. Use your browser's inspect capability (right-click on an element and choose inspect) and you'll see the HTML structure of your page. On the right side, you'll also be able to see all of the styling applied to each DOM element, including padding. Then just use CSS to change that style. You can find lots of info about styling in Mendix, but this link is a good place to start