This page demonstrates a bug (?) with Mozilla 1.7a and higher combined with the overLIB javascript library.
After loading this page, slowly move the cursor over the first link, while looking at the top left corner of the page. Before the popup shows up, it will appear at the top left corner for half a second before showing up next to the cursor. However, this only happens on first load. Moving the cursor over this first link will again will result in normal behaviour (ie. it won't show up in the top corner).
To duplicate this behaviour without reloading, move the cursor to the bottom text and back again. The popup will now show up at the bottom location when moving back to the top link.
What's interesting is that on first load, moving the cursor over the 2nd link will not result in the popup showing up in the top corner. The difference between this link and the top one is that this one does not have a href="...".
This only happens with overLIB 3.51/4.00 on Mozilla 1.7a or 1.7b (Windows) as well as Firefox trunk gtk2 20040325 build (Linux). It does not affect Mozilla 1.6b or lower. This does not occur with overLIB 3.50 on any versions of Mozilla.
This was reported as bug 238879.