Shift + scroll in canvas should scroll horizontally

[saborrie]

It is a standard behaviour that scrolling a mouse wheel while holding the shift key scrolls horizontally. Try it on normal web pages on chrome, or really anything that uses normal scroll behaviours.

The canvases in dark ought to do this too, but don't. The shift key is currently ignored.

[pbiggar]

Good point, thanks!

Fyi, we're not working on darklang "classic" - our intent is to take the lessons into replacement based on the new stack. That said, this is a good point when we get there.