I did a quick google search to see if I was doing the CSS wrong, or if there's a documented bug.
I found nothing, but then got an idea that should seem pretty obvious.
canvas.onmousedown=function(evt){
...
evt.preventDefault();
return false;
}
I tested that out to see if it was a browser function causing the CSS inconsistency, and it worked like a charm, I now have full control of the cursor's style.
Here's the link, if anyone's curious.
Just thought I'd share this in case anyone else runs into this glitch.