[whatwg] seamless iframes and event propagation

Chaals McCathieNevile w3b at chaals.com
Wed Jul 11 03:38:42 PDT 2012

On Tue, 10 Jul 2012 01:26:13 +0200, Ojan Vafai <ojan at chromium.org> wrote:

> 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.

The first two of these use cases make no sense to me (which might just be  
because I am not very bright, or missing something...)

> 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.

Using javascript for keyboard shortcuts is not a good idea in the first
place. People will keep doing it instead of something more scalable to the
web like improving their accesskey implementations, but we should not be
encouraging it, by making it easier to do the wrong thing instead of
somethign useful.

(The problem is that javascript key handlers generally do not
internationalise well, are awful across a wide range of devices, and are
almost guaranteed to fail future devices).

> 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.

Isn't this why we introduced native drag and drop to HTML?



> 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

Chaals - standards declaimer

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