Paul_o_b - 8:19 am on Sep 20, 2012 (gmt 0)

Yes outlines have always historically been buggy.

e.g.
IE8 incorrectly places the outline on inline elements when the parent element has the value text-align:justify. The outline remains at the exact position had justify not been used and will therefore be misaligned with the element it refers to depending on how far the text has been moved when justified.

Firefox 3.5 and under will draw the outline outline around the content of an element that has overflowed its boundaries rather than around the element’s actual set dimensions.

Someone may want to see how MSIE behaves.

In IE9 the left border gets covered.

In IE8 the left and top borders get covered.

IE7 doesn't understand outlines and ie6 doesn't understand hover on anything but anchors.:)
(IE must be in standards mode of course or none of them will work)

Apologies I missed the part about in the OPs original post referring to cells so my previous example is probably of no use.