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From: Terence de Giere
Date: Apr 20, 2003 1:39PM
Subject: Re: Dreamweaver Layers
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Dreamweaver layers, depending on the setting in the preferences, use
either the <div> element or the <span> element to absolutely position
blocks for page layout. Once constructed, the layers can also be
converted to '3.0 browser' compatible layout by converting them to
tables. As with tables, visually creating a layout this way can result
in page content sequence problems when the page is experienced in non
visual modes.
While the page may look fine visually, the sequence and nesting of the
<div> sections may not turn out to be what one expected when the
interface is constructed using the visual interface tools in the
Dreamweaver graphical mode. It may be necessary to manually renest and
resequence certain <div> blocks to get the page to linearize properly
for accessibility (assuming any of the <div> sections are nested. In
other words, Dreamweaver is automatically writing code based on how one
draws the layers, but doesn't have the ability think, which is what the
developer of the page always needs to supply.
Normally the <div> element should be used for blocking out layout - the
<span> element is for inline use: one cannot, for example, legally put
<span> around a paragraph.
Excessive nesting of <div> elements may cause problems with Netscape 4
browsers, which might hang up, just as it does with deeply nested tables
(such a page however will work in Netscape 4 if Cascading Style
Sheets(CSS) support is manually turned off, or the style sheet is not
served with the page to this browser, the problem is with Netscape 4's
limited CSS support).
With absolute positioning done rightly, the sequence of the page content
as it would be rendered with a screen reader, audio browser, or text
browser can be optimized for accessible use while the visual appearance
is as desired for a GUI (Graphical User Interface). This is the
accessible advantage of CSS positioning over tables.
Absolute positioning does have some drawbacks visually if the layout
blocks are fixed - if a user needs to enlarge text to read it, the text
may flow out of view or overlap other text, an effect that does not
occur when tables are used for positioning. There are additional CSS
rules that can help with this however. Graphic designers seem to have a
penchant for fixed size layouts, while accessibility is best with
relative sizing of page elements. Relative sizing allows the users with
visual impairments but who can still see a page which is enlarged or
with enlarged text, to read the page. As an example, designers seem to
prefer font sizes in the 8 to 10 point size on web pages for the main
text, while children and older adults appear to perform best with about
16 point font sizes. A design that can handle moderate size variations
for fonts without display and major format problems will be more
universally adaptable to these typical needs.
Terence de Giere
= EMAIL ADDRESS REMOVED =
-------------------------------------------
Candace Egan < = EMAIL ADDRESS REMOVED = > wrote:
Is anyone familiar with Dreamweaver layers and whether using them causes
accessibility problems?
Candace
--
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Candace Lee Egan
Educational Technology Consultant
Academic Innovation Center
California State University, Fresno
(559) 278-5070
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