Shared components used by Firefox and other Mozilla software, including handling of Web content; Gecko, HTML, CSS, layout, DOM, scripts, images, networking, etc. Issues with web page layout probably go here, while Firefox user interface issues belong in the Firefox product. (More info)
I've split this off from bug 300808.
When you have nested elements, and the ancestor element has a tooltip attached
to it, moving from the one nested element to the other, should not let the
tooltip disappear inbetween.
IE6 is doing this correct.