[whatwg] Submit controls should be barred from constraint validation in favor of a new pseudo-class

[Mounir Lamouri]

Hi,

It sounds like currently the specifications want explicitly to have all
submit controls being subject for constraint validation [1] which seems
to be a weird idea. Given that only setCustomValidity() can be used on
those controls, the only use case I see is to set the submit controls
invalid when the form is invalid thus having :invalid style applying to
them.

If the given use case is correct, I think we should make all submit
controls barred from constraint validation and introduce a new
pseudo-class allowing to style submit controls when their form is
invalid. This would prevent having invalid elements styled exactly like
the submit controls (which would let the user think the submit control
is invalid) and it would prevent having :valid applying on buttons for
no apparent reason.
This pseudo-class would apply on all submit control inside a form which
has at least one invalid element subject for constraint validation.
Note: disabled submit controls could be excluded, I've no strong opinion
about that considering it's really easy to add :enabled in the CSS rule.

Current Gecko nightlies (and next beta, beta7) have a
:-moz-submit-invalid pseudo-class. Submit controls can still be marked
invalid but that might change before the final release if there is an
agreement that :-moz-submit-invalid is a better way to fulfill the need.

As a side note for web authors on this list, :-moz-submit-invalid
currently has a default style on Firefox but that is very likely going
to change for beta8.

[1] all button types are barred except the submit one:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-button-element.html#the-button-element

Thanks,
--
Mounir