I'm having an issue getting the HTML5 Canvas to display in any of my browsers on OS X 10.8.3
I've got it working in Firefox, and moving my scroll wheel up scrolls in, but I can't scroll back out (OS X Natural Scrolling enabled) -- but if I switch it works in Firefox, but no change in Safari in Chrome.
Ok, so the canvas element is accelerated on the graphics card in some browsers. You could be having issues with browser/OS/graphics card incompatibility, though on an Apple computer, it should be pretty tested before release. You could try to disable GPU acceleration of canvas in chrome. I think it's under chrome://flags .
As for scrolling, Firefox fires different events than Chrome and others, and I try to take that into account. As for Natural Scroll, I don't know how that factors into the DoM event model, but after a search, I have not found anything really firm to support OS X scrolling events.