[CSS21] Overflow/clip and stacking contexts

Hi,

Can the 'overflow' and 'clip' properties create a new stacking context, 
like 'opacity'? If they can not, I have trouble seeing how to implement 
them while also implementing the proper painting order described in 
appendix E.

In particular, several steps refer to descendants of a box that creates 
a stacking context. The overflow and clip properties that apply are not 
only that of each descendant, but also that of all their ancestors.

I guess that would be possible, but the implementation gets much more 
complex.

-- 
Simon Sapin