Closed Bug 740856 Opened 9 years ago Closed 4 years ago

Support pseudoelements syntax in xbl

Categories

(Core :: XBL, defect)

defect
Not set
normal

Tracking

()

RESOLVED WONTFIX

People

(Reporter: enndeakin, Unassigned)

References

()

Details

XBL 2 has a pseudo attribute to allow specific anonymous content nodes to match as a pseudo element.

For example:

<xbl:content>
  <image src="hello.png" xbl:pseudo="icon"/>
</xbl:content>

would allow:

element::icon {
  border: 1px solid red;
}
I think this is bad design. The proposed CSS pseudo-element should probably
be a functional notation. For example:

  ::xbl-content(icon)

That allows a lighter impact on the CSS parser and a greater extensibility.
Indeed.  For example, implementing the proposal in comment 0 would require a pretty complete rewrite of how pseudo-elements are handled in the style system in Gecko.
I'm assuming that the concern above only applies when extended to arbitrary pseudo elements. Note that xbl2 only defines five specific pseudoelements that are allowed:
  value, choices, label, repeat-item, and icon

That said, custom pseudo elements could also be supported via a different syntax, something akin to the one described in comment 1, since there will likely be value of it in toolkit bindings.
Blocks: XBL2
If the set of possible pseudo-elements is fixed and not too big, then comment 2 doesn't apply, yes.
Web Components \o/
Status: NEW → RESOLVED
Closed: 4 years ago
Resolution: --- → WONTFIX
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