Scrollbar can't be used due to header rotation

[ticky]

On Windows, it is not possible to drag the scrollbar at the top of the page, as the mouse rotation of the header kicks in and overrides its use.

[unconed]

This happens on OS X too, and appears to be a WebKit bug:
https://bugs.webkit.org/show_bug.cgi?id=19033

Confirmed in Safari 6, Chrome 29-31.

[ticky]

Just confirmed on OS X, Safari 6.1 also exhibits this behaviour.

A potential workaround could be to ignore clicks in that area when we expect a scrollbar to exist.

var scrollbarWidth = 20;
document.addEventListener('mousedown', function (e) {
  if (document.body.offsetHeight > window.innerHeight && e.pageX > window.innerWidth - scrollbarWidth) {
    return;
  }
  e.preventDefault();
});

This isn't a great solution - it doesn't really take into account OS X's on-scroll scrollbar visibility, nor would it work too well if the user heads to the corner to click the settings button in that area, but it probably solves more problems than it causes.