Re: Overflow-clipping of filters with fixed-pos/abs-pos descendants

On Jan 12, 2015, at 9:40 PM, Robert O'Callahan <robert@ocallahan.org> wrote:

> On Tue, Jan 13, 2015 at 5:21 PM, Simon Fraser <smfr@me.com> wrote:
> But Firefox and WebKit do clip the blue and yellow boxes if you replace the filter with opacity. Chrome does not.
> 
> The Web compat constraints around 'opacity' are probably a lot tighter than around 'filter', since the former has been around a lot longer. So it might make sense to treat them differently. In particular, I'd be quite afraid to implement option #1 or option #2 for opacity.


Agreed; both options would have serious compat risk, but it would be a shame to have different behaviors for two properties (opacity and filters) that are essentially the same.

What is the nature of the fix you made in Firefox? How, conceptually, can you render a group of two translucent elements with different clips, other than by building a complex clip region?

Simon