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[css-regions] Changing behavior of a named flow without a region chain

From: Alan Stearns <stearns@adobe.com>
Date: Tue, 23 Apr 2013 11:10:38 -0700
To: "www-style@w3.org" <www-style@w3.org>
Message-ID: <CD9C1CAE.292B3%stearns@adobe.com>
Hey all,

The CSS Regions specification currently has this paragraph:

A named flow needs to be associated with
a region chain (one or more CSS regions)
for its content to be visually formatted.
If no region chain is associated with
a given named flow, the content in
the named flow is not rendered:
it does not generate boxes
and is not displayed.


You need a matched pair of flow-into and flow-from to flow the content
through a region chain. If you only use flow-into the content is taken out
of the normal flow and basically disappears. This is problematic for a few
reasons. It duplicates what's already done using display:none. It adds one
more thing to check if your content is not being displayed. It's difficult
to explain to someone new to named flows. And it adds a failure mode that
isn't useful by itself (you should use display:none if you want this
effect).

So I'd like to change the behavior of a named flow that does not have a
region chain. Instead of the two properties working like this:

---
The flow-into property takes content out
of the parent flow and places it in a named flow.

The flow-from property assigns a region chain to a named flow.
---

I'd like the properties to work like this:

---
The flow-into property assigns content to a named flow.

The flow-from property assigns a region chain to a named flow,
takes the named flow content out of the parent flow
and formats it in the region chain.
---

So a named flow without a region chain formats its content as normal, in
place in the parent flow. It's only when you add flow-from that the
display moves from its original location to the region chain. The behavior
is exactly the same when you have a matched pair of flow-into and
flow-from. The only change is when you're lacking the flow-from, the
content does not disappear.

Thanks,

Alan
Received on Tuesday, 23 April 2013 18:11:26 UTC

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