[whatwg] seamless iframes and event propagation

[Ojan Vafai]

I'd like to see us add event propagation into the parent document for
seamless iframes, e.g. key and mouse events inside a seamless iframe should
be refired on the iframe element.

Use-case 1: A global key event handler for keyboard shortcuts. Without
propagating the events, you need to add a key handler to each seamless
iframe's root in order for these keyboard handlers to work when the iframe
has focus.

Use-case 2: A dragging UI. Without event propagation, if you don't add
handlers to the iframe's root, you would just stop dragging when the mouse
is over seamless iframes. In addition, the coordinates of the mouse event
should be changed to the parent document's coordinate space when it is
refired on the iframe, otherwise your code needs to know when it's over an
iframe.

We should fire two events. One inside the iframe and one on the iframe
element itself (in the parent document). Any pointers to DOM nodes in the
event would need to be nulled out in the event fired in the parent document
if the seamless iframe is cross-domain and non-CORS accessible.

This makes seamless iframes more seamless. Most existing keyboard shortcut
and dragging JS code would magically keep working without needing to know
anything about seamless.

Use-case 3: Making an email client that wants the content of the email
isolated from the client's UI, but doesn't want a nested scrollbar (i.e.
the editable area sizes to the emails size). In this case, you don't want
to inherit the CSS for the mail client into the email's content. Similarly,
you may not want your global keyboard handlers to run when typing in the
editable area.

Similar to Adam's allow-seamless proposal, I'd like to see seamless have
the ability to tweak which bits of the frame act seamlessly. Adam's
proposal has inherit-styles. We could also add propagates-events to
allow-seamless. Both of those would be off by default. For seamless, we
could have no-inherit-styles and no-propagate-events in order to disable
either behavior, also off by default.

Ojan

On Sat, May 26, 2012 at 5:16 PM, Adam Barth <w3c at adambarth.com> wrote:

> Hi whatwg,
>
> I've added a proposal to the wiki
> <http://wiki.whatwg.org/wiki/AllowSeamless> about letting a document
> indicate that it is willing to be displayed seamlessly with a
> cross-origin parent.  This proposal is a refinement of the approach
> previously discussed in this thread:
> <http://old.nabble.com/crossorigin-property-on-iframe-td33677754.html>.
>
> Let me know if you have any feedback.
>
> Thanks!
> Adam
>