Currently Armor Check penalty applies to strength, dexterity, and constitution based skill checks unless they have the attack trait. This works for most things but it has a few odd results specifically there are some skill uses which, despite being dex based, I don't think should have an armor check penalty, specifically things that just involve the hands not the whole body:
Stealth(Conceal on Object)
Theivery(Disable Device & Pick Lock)
You could also make a case for Acrobatics (Grab Edge) though that is less straightforward.
Additionally this makes Break Open an Attack which I don't really think it should be.
I propose that the armor check penalty become a tag that certain skill uses have (climb, jump, swim, stealth, tubmble etc.) rather than the default for all Str, Dex, and Con based skill checks.