> Find the position of the layer, then see what's > underneath it. I'm not sure how to do that last one, > except for looping through all elements on the page > and seeing if their position matches the position > of the layer. That would be the x-browser way of doing it; if it's IE only there's a proprietary method you can use which finds the nearest element to a given set of co-ordinates - http://msdn.microsoft.com/workshop/author/dhtml/reference/methods/elementfrompoint.asp This can also be prototyped in 1.4 or later gecko builds; http://www.codingforums.com/showthread.php?s=&threadid=21674