from what i’ve been reading, there are more pseudo classes coming in future versions of the spec, so it would be worth while for PG to keep on top of supporting these in the visual editor (imho).
i’m also now noticing that, if you use a combinator in your CSS (like the > or the ~) the rules involved will not show up in the ACTIVE tab, whether you use a pseudo class toggle or not.
if the rule is standalone (only affects a single element, like styling a link), then it will pop up, but if a combinator is involved, then it will not… this kind of hobbles the utility of that feature in PG.