proposed element() CSS function

I've updated my proposal:
http://people.mozilla.com/~roc/SVG-CSS-Effects-Draft.html
with a rough outline of an "element()" CSS function that would overcome some
of the limitations of the CSS url() syntax.

Let me summarize the motivation:

We need a flexible way to reference subtrees of DOM documents. The CSS url()
syntax is inadequate for the following reasons:

   - url() values are relative to the CSS stylesheet so there is no way for
   an external stylesheet to reliably reference an element in the styled
   document.
   - An external url() reference refers to a "resource document" with a
   given URI. There is no way to reference an element in a subdocument of the
   styled document, such as a specific IFRAME. In general we may want to follow
   a path of subdocument references and external resource document references.
   - The SVG WG has already begun defining semantics for url()s with
   fragment references, which make it clear the referenced fragment must be
   interpreted in the context of the whole document. When we reference SVG
   paint servers from non-SVG content, we need to interpret the subtrees as
   isolated fragments.

Rob
-- 
"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
53:5-6]