Don't you just need to enable a 'fullscreen in browser' setting?
The problem is it doesn't stretch 640 x 480 to widescreen monitors, it leaves canvas background color on right, if the unbounded scroll is off and 2 spaces between a canvas, if the unbounded scroll is on
I've tested with fullscreen using project settings and browser plugin (weird, i've seen transparent margins on Chrome)
let me know if is not possible.