In IE8 (and only IE8 as far as I can tell) when calling fadeIn() on an element which has a progid:DXImageTransform.Microsoft.Alpha(Opacity=85) filter set through a stylesheet, that filter ends up as DXImageTransform.Microsoft.

After some testing I found that somewhere during the fadeIn() the set function of jQuery.cssHooks.opacity is called with an empty value for opacity, which causes the opacity variable in there to be empty and thus "stripping" the end of the filter on the last line of that function.

I found this on jQuery 1.7.2, but a quick check confirmed that it's still present in 1.8.0

Repro: ​http://jsfiddle.net/sk434/

The jQuery docs suggest that live() is now deprecated and that we should now use on(). The fact is that on() does not function in the same was as live(). For example, I am using the jQuery Tablesorter plugin along with its pager extension. Using on() I cannot attach event handlers to table elements other than the first page viewed, whereas live() works perfectly on all pages.

Keep live() alive!!!!

I think it would be worthwhile adding an entry for $.cssNumber to the API docs, alongside the existing entry for $.cssHooks.

At present, the only mention of it is right at the bottom of the entry for $.cssHooks, and so it's very easy to miss.

The main reason I think it might be a useful addition is for anyone wondering why setting the line-height style without a value does not give the same results as setting the font-size style without a value, e.g.:

        var size = 10;
        el.css({ fontSize:size, lineHeight:size });

Personally, I'd add it to both the "CSS" and "Mainpulation -> Style Properties" categories, as those would be the places I'd be looking if I had the aforementioned issue.