misstery:
If you go into full screen mode by pressing F11 on your keyboard you can still use the space bar to zoom, (works on Firefox & Iron Browsers.)
And in Chrome and Comodo Dragon. Using that game feature where it goes full screen is the same as right clicking in the game screen and selecting zoom. All it does is magnify the screen. The F11 function is much better to use to fill your screen up. The graphics don't get fuzzy and the spacebar does work as the zoom function.
A minor workaround with the F11 key, if it doesn't enlarge the screen, is to minimize it, maximize it and then hit F11.