This last change doesnt look safe – ptr is set by code other than mouseover, so may be pointing at something other than the hover row. That could be fixed by using a different variable (eg hover_row). (Perhaps you did this – I dont see the change in github yet).

But, I think there is a bigger issue.

Every time the mouse moves from one sub-element of a row to another sub-element of a row, we get both a mouseout and a mouseover, and so the above code (even after the changes) removes and re-adds the class.

This will happen eg when moving from one td to another in the same row. But for grids whose cells have complex contents could be happening *a lot* within a single td.

I think the code as it stands is “correct” (Im assuming the mouseout is guaranteed to come before the mouseover, but havent checked that that is the case), but is certainly going to fire far too often.

It seems like you could check whether relatedTarget and target are contained in the same row, and only add/remove the class when the row actually changes.

That would somewhat negate the above change – because now you do two “closest” calls per mouseover/mouseout. But I suspect that most of the time is spent in adding/removing the class (because it causes the document to reflow).

Mark

The ideal solution would be to use the css pseudo class :hover in all browsers that support it (ie everything except ie6), and not have the event handlers at all for most browsers.

Unfortunately, you cant do that and stay compatible with themeroller, as far as I can tell (this seems to be a flaw with jquery-ui/themeroller).

Mark