[stevejohnson]

It's not a hard problem; you just need a little JavaScript to update your canvas's width/height attributes when the size of the DOM element changes. Then you can just use CSS to fill the window with your canvas, and use the fullscreen API to take the browser fullscreen.

[akvlad]

Well, it's also not a simple as you describe. You might have objects within the canvas that might also need to be resized, images, text, bg images, bounding borders, etc. All these things will need to be taken into consideration when being scaled or resized.