Did windows update 2846071 break the handling of window.event.clientX clientY?

Question

Did windows update http://support.microsoft.com/?kbid=2846071 break the handling of window.event.clientX and clientY? It seems that Windows 7 machines using IE 9 or 10 now return something that looks like the window position (top left corner) rather than the mouse position within the window. The numbers look accurate, but may be negative.

Or is that a "fix" and I should really be using something else for the mouse position.

I was using it in window.onbeforeunload to detect a user leaving the page without logging out and giving them the boot, but I'm disabling that today until I figure this out.

Answer 1

This link: http://social.technet.microsoft.com/Forums/windows/ja-JP/0985853c-0376-48d0-b748-c4259c0fc4a9/26356260321250312525124641252112512-kb2846071 implies that this was an intentional outcome.

It may be that this was changed to address the security concern here: http://blogs.msdn.com/b/ie/archive/2012/12/13/update-to-alleged-information-and-security-issue-with-mouse-position-behavior.aspx