[whatwg] seamless iframes and event propagation

Dimitri Glazkov dglazkov at chromium.org
Wed Dec 5 07:38:36 PST 2012

On Wed, Dec 5, 2012 at 3:49 AM, Anne van Kesteren <annevk at annevk.nl> wrote:

> On Wed, Dec 5, 2012 at 12:37 PM, Hayato Ito <hayato at chromium.org> wrote:
> > Some kinds of events should be always stopped at the shadow boundaries.
> > See
> http://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#events-that-are-always-stopped
> It's not entirely clear to me what that means. If an <img> ends up
> interleaved in a shadow tree through a <content> element, surely the
> node tree ancestors of <img> should still get the load event? Does the
> shadow tree not want to know this too?

Yes, the intent is that in the the events from nodes, distributed to
insertion points should feel as if there wasn't any shadow tree around them:

> Also, is input missing from that list? A short explanation along with
> that list would probably be good so we know what the criteria are.

Sure, https://www.w3.org/Bugs/Public/show_bug.cgi?id=20248. I can't
remember now why I left it out, but I'll find out.

> > The Shadow DOM spec does not require adjusting mouse coodinates. I
> > think every shadow trees in one document *share* the same x-y
> > coodinates.
> There are coordinates relative to the target though, see:
> http://dev.w3.org/csswg/cssom-view/#extensions-to-the-mouseevent-interface
> I suppose if you do not initialize those on the object but instead
> compute them on getting it might work without having to adjust
> matters.

Whoa, good catch. https://www.w3.org/Bugs/Public/show_bug.cgi?id=20249
We do indeed cache/reset this value when retargeting in WebKit, but this
still needs to be specified.

> > I don't have a clear idea about what should be cloned when crossing
> > boundaries. That's unclear for me.
> Okay, I guess that remains then.

For shadow DOM, we definitely don't need cloning. But it seems critical for
seamless iframes. Looking forward, when we do add "isolated" to shadow
trees, the shadow DOM will use this plumbing too.


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