Cannot scroll when intro guide is active

[Narretz]

When a highlighted element is partly outside the viewport, then it should be possible to scroll to see it. Atm intro-guide is hijacking the scrolling. I get some ugly jittering when trying to scroll, and I cannot actually scroll at all. Tested in FF and Chrome.

[Narretz]

I've solved this by re-drawing the hole in the canvas after a debounced scroll. Doesn't look too pretty (Maybe it can be animated?), but it works