296098 - Pseudo element selectors should be able to match non-anonymous boxes

Status: RESOLVED WONTFIX

(Core :: CSS Parsing and Computation, defect)

Description

[Doron Rosenberg (IBM)]

Based on an irc conversation.  Filing it for reference.

<doron> bz: so pseudo elements, seems ::value is defined in
http://www.w3.org/TR/css3-ui/#pseudo-value.  XForms needs it (and is one of the
few languages where it makes sense).  Would there be a way to XForms to specify
the value of the pseudo elmement, or do we currently do all the calulations in
the css engine?
<bz> doron: so this is basically for cases when a single XML element has
multiple things as part of its rendering, right?
<bz> doron: like a file input?
<doron> right
<bz> doron: gotcha.  And for XForms we do that via XTF anonymous content...
<doron> <xforms:input><xforms:label/></xforms:input>
<doron> we create an anonymous html:input, which ::value would select
<bz> doron: That's a major problem, actually
<bz> doron: we can't have "::value" and "input" matching the same layout object
<bz> doron: in the current CSS arch
<bz> doron: s/CSS/style system/
<doron> why not? Or do I not wantt o know?
<bz> doron: the current assumption is that pseudo-elements are just that --
pseudo-elements
<bz> doron: that is, they have no real tag corresponding to them
<doron> bz: so could xtf/xforms create these pseudo-elements?
<bz> doron: I'd have to think about it.  In any case, this would require changes
to XTF and the frame constructor in some way....

Comment 1

[Doron Rosenberg (IBM)]

bz: got a rough sizing on how much time it would take to fix this?  And could
someone without deep CSS knowledge be able to do it?

Comment 2

[Boris Zbarsky [:bzbarsky]]

Nope, not even a rough estimate.  No idea how much code would need to be
rewritten/redesigned....  Knowing some CSS would be needed (understanding
exactly how selectors work).  Knowing the details of CSS layout would probably
not be necessary.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I don't think there's still any demand for this (and I don't think it was a good idea in the first place).