300666 - :root selector should act as the selector for the bound element in a scoped stylesheet

Status: RESOLVED INVALID

(Core :: XBL, defect)

Description

[Martijn Wargers (dead)]

This spun off from a conversation with Boris. He advised me to file a bug on this.

I'll attach a testcase that exactly explains what this bug is about.

Comment 1

[Martijn Wargers (dead)]

Attachment: testcase

The data uri in the testcase is this: 
:root { background-color: green;}

Comment 2

[Boris Zbarsky [:bzbarsky]]

I'm also sort of wondering what the ' ' and '>' combinators should do in scoped
stylesheets.  Should they cross the scope boundary, or no?

Right now we have :-moz-bound-element which sorta matches the bound element, but
I'm not sure how well that works (we have no uses in our chrome, and Martijn's
attempt to use it earlier today didn't work the way I would have expected it to).

Comment 3

[Hixie (not reading bugmail)]

This bug is invalid. :root should match the root element _only_. (Otherwise
there is no way to match a root element in a binding stylesheet.)

:-moz-xbl-bound-element should match the bound element.

See http://www.hixie.ch/specs/xbl/XBL2.html#shadow0 to see what the current
thinking for W3C XBL is as far as the combinators go.

Comment 4

[Boris Zbarsky [:bzbarsky]]

The first question is whether a binding stylesheet should match anything outside
of the binding scope.  It sounds like you're saying the answer is yes... Why is
that?  That seems odd to me.

Comment 5

[Hixie (not reading bugmail)]

It shouldn't _match_ anything outside the shadow tree (apart from the bound
element), but it can refer to such elements. For example, in a binding for an
<option> element, one might imagine:

   select[multiple] > option:moz-bound-element

...being a useful selector (that would only match if the option in question is
in a multi-select widget).

Comment 6

[Martijn Wargers (dead)]

So this bug can be marked invalid, right?

Comment 7

[Boris Zbarsky [:bzbarsky]]

Yeah, I guess so...