is(':active') will report false for button in active state. $('*:active') will still select this element as active. Workaround: use $('*:active').filter(el).length > 0 instead of $(el).is(:active).

In code:

el.is(':active') == $('*:active').filter(el).length > 0;

should always be true. It is not.

Example fiddle:

http://jsfiddle.net/atotic/HzSY6/