HTML does not define a disabled attribute for fieldset: http://www.w3.org/TR/html4/interact/forms.html#h-17.10 so it should not match :enabled/:disabled.
Created attachment 194464 [details] [diff] [review] Patch This came from bug 84400. My bad. Testcase can be found here: http://beaufour.dk/tmp/enabled-false.xhtml
Checked in to trunk
Note that when we start implementing parts of Web Forms 2 which I believe is planned on trunk we do want to support this.
Checked in to 1.8 branch