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Re: [UndoManager] Disallowing live UndoManager on detached nodes

From: Maciej Stachowiak <mjs@apple.com>
Date: Wed, 22 Aug 2012 22:44:23 -0700
Cc: Ryosuke Niwa <rniwa@webkit.org>, Glenn Maynard <glenn@zewt.org>, public-webapps <public-webapps@w3.org>, Kentaro Hara <haraken@chromium.org>, Sukolsak Sakshuwong <sukolsak@google.com>, Adam Barth <abarth@webkit.org>, Ehsan Akhgari <ehsan@mozilla.com>, Jonas Sicking <jonas@sicking.cc>, Olli Pettay <Olli.Pettay@helsinki.fi>, Dimitri Glazkov <dglazkov@chromium.org>
Message-id: <43680DD2-428F-425C-B763-E63710023AB3@apple.com>
To: Ojan Vafai <ojan@chromium.org>

On Aug 22, 2012, at 6:53 PM, Ojan Vafai <ojan@chromium.org> wrote:

> On Wed, Aug 22, 2012 at 6:49 PM, Ryosuke Niwa <rniwa@webkit.org> wrote:
> On Wed, Aug 22, 2012 at 5:55 PM, Glenn Maynard <glenn@zewt.org> wrote:
> On Wed, Aug 22, 2012 at 7:36 PM, Maciej Stachowiak <mjs@apple.com> wrote:
> Ryosuke also raised the possibility of multiple text fields having separate UndoManagers. On Mac, most apps wipe they undo queue when you change text field focus. WebKit preserves a single undo queue across text fields, so that tabbing out does not kill your ability to undo. I don't know of any app where you get separate switchable persistent undo queues. Thins are similar on iOS.
> Think of the use-case of a threaded email client where you can reply to any message in the thread. If it shows your composing mails inline (e.g. as gmail does), the most common user expectation IMO is that each email gets it's own undo stack. If you undo the whole stack in one email you wouldn't expect the next undo to start undo stuff in another composing mail. In either case, since there's a simple workaround (seamless iframes), I don't think we need the added complexity of the attribute.

Depends on the user and their platform of choice. On the Mac I think it's pretty much never the case that changing focus within a window changes your undo stack, it either has a shared one or wipes undo history on focus switch. So if GMail forced that, users would probably be surprised. I can imagine a use case for having an API that allows multiple undo stacks on platforms where they are appropriate, but merges to a single undo stack on platforms where they are not. However, I suspect an API that could handle this automatically would be pretty hairy. So maybe we should handle the basic single-undo-stack use case first and then think about complexifying it.

> Firefox in Windows has a separate undo list for each input.  I would find a single undo list strange.
> Internet Explorer and WebKit don't.
> While we're probably all biased to think that what we're used to is the best behavior, it's important to design our API so that implementors need not to violate platform conventions. In this case, it might mean that whether text field has its own undo manager by default depends on the platform convention.
> Also, another option is that we could allow shadow DOMs to have their own undo stack. So, you can make a control that has it's own undo stack if you want.

Again, I think it's not right to leave this purely up to the web page. That will lead to web apps that match their developer's platform of choice but which don't seem quite right elsewhere.

BTW, I don't think the API should impose any requirements on how browsers handle undo for their built-in form controls. I have not read the spec close enough to know if that is the case.


Received on Thursday, 23 August 2012 05:44:56 UTC

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