Re: [css3-backgrounds] Should a non-zero border-radius create a new stacking context ?

On Tue, Nov 23, 2010 at 3:03 PM, Sylvain Galineau <sylvaing@microsoft.com>wrote:

>  What complexity would have been added for authors by creating new
> stacking contexts for overflow != visible ?
>

The complexity of "setting this property value over here has this apparently
unrelated side effect over there".

I'd argue the latter is what is actually expected by most, especially
> so when overflow == hidden. Having outside elements layer underneath the
> children of an element with overflow:hidden - never mind clipped children -
> is neither easy to explain nor is it common practice.
>

I think it's easy to explain. The explanation is "'overflow' does not affect
z-order".

Now, the rest of the CSS z-ordering rules are not easy to explain, but
that's a different problem :-).

  Not sure what we mean by 'reasonable behavior'. Reasonable for authors or
> implementors ?
>

Both, actually.

Group opacity means "composite all the elements of the group together into a
single image, then composite that image into the destination". There's no
rational way to extend that to handle situations where the elements of the
group are interleaved in z-order with other elements that are not part of
the group.

Rob
-- 
"Now the Bereans were of more noble character than the Thessalonians, for
they received the message with great eagerness and examined the Scriptures
every day to see if what Paul said was true." [Acts 17:11]