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Re: [css3-selectors] :parent selector

From: Steven Pemberton <steven.pemberton@cwi.nl>
Date: Thu, 28 Sep 2006 23:41:17 +0200
To: "David Hyatt" <hyatt@apple.com>, "Patrick Lauke" <P.H.Lauke@salford.ac.uk>
Cc: www-style@w3.org
Message-ID: <op.tglyi3zvsmjzpq@acer3010.lan>

On Mon, 25 Sep 2006 10:54:56 +0200, David Hyatt <hyatt@apple.com> wrote:
> As I've said a couple of times before, my real objections to a parent  
> selector are
>
> (a) I don't like selectors that are incompatible with incremental  
> rendering (since you risk displaying incorrectly styled content when  
> doing incremental rendering while a page loads).  (This problem would be  
> especially bad for parent selectors... moreso than say, :last-child).
>
> and
>
> (b) The performance of this selector would be terrible.

I think there needs to be a higher-level discussion, because there seem to  
be some hidden assumptions in the current discussion that need to be  
surfaced:

1. Are Selectors only for CSS, or are they intended to be used in other  
contexts as well? If the latter, then deciding whether a selector is  
needed shouldn't be based on grounds of rendering alone.

2. Who is responsible for a page rendering incrementally: the CSS  
designers, or the page author? If the latter, then the CSS specification  
can simply mark certain selectors as obstructive to incremental rendering,  
but still allow them for use.

3. Does 'incremental rendering' mean rendering correctly immediately, or  
does it mean showing the page as it loads, even if not in its final form?  
Most browsers in my experience do the latter; for instance if the  
stylesheet or embedded images are slow to load, then they will render as  
best they can until they know more. But if 'incremental rendering' is code  
for 'doesn't need a DOM tree to render' then this inherently limits the  
choice of selecters, whether the result is rendered incrementally or not.

Best wishes,

Steven Pemberton
Received on Thursday, 28 September 2006 21:41:24 GMT

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