compositing and blending of background images

All,

the compositing and blending spec currently defines how one can apply these
graphical effects to background images [1].
I've mentioned before that these really belong in the backgrounds and
borders spec. This would also enable them to be part of the background
shorthand [2].

In the last couple of weeks I have gotten several requests on when this
feature will be available, but I've also gotten feedback that this is
really something that SVG should be fixing.

My questions are:
- is this a feature that we want to implement? Looking over the mozilla and
webkit code bases, it seems simple to implement (WebKit already support
compositing today)
- if so, where should this live? Should it move to B&B or stay in the
compositing and blending spec?

Thanks!
   Rik

1:
https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#cssbackgroundsyntax