Thanks a lot for this, Travis, it's a great help.

Would you mind opening an issue ticket in GitHub for this? That will make sure it doesn't get lost and serves as a checklist for me.

Reading over your code changes I think you're right that it works fine if the position:fixed element is a child of the body, but if the position:fixed element is a descendant of another positioned element then it won't work right because it still subtracts the position of that parent element.

Actually I think that if it's position:fixed we can shortcut past all the getBoundingClientRect stuff and just use the left/top/bottom/right currentStyle properties of the target element directly (except in IE6 of course, which we'd let fall through to the current code). Do you see any problems with that?

I'd also want to verify that this method of positioning responds correctly when the element moves due to animation etc.

Thanks, Travis, I'll try to get your changes integrated when I have time.

Yeah, no problem. Don't rush yourself. The reason I put some work into diagnosing the issue is so that I can fix it myself, for my own purposes, straight away, so I'm not affected by the wait for you to fix it. With the sample code I posted, others can do their own temporary fixes too.

And thank you for what you've already done on PIE. Even if it isn't (yet) perfect, it's still a lot less work than implementing the same stuff from scratch.