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OnChange in dropdown combo box used for navigation

From: STELZER,MELINDA (Non-HP-PaloAlto,ex1) <melinda_stelzer@non.hp.com>
Date: Tue, 18 Dec 2001 16:42:05 -0500
Message-ID: <AE5322A8186ED311A0CF009027403BC40F6CBB3C@xpa01.corp.hp.com>
To: w3c-wai-ig@w3.org
I was reading the discussion below concerning two different ways of handling
pages that use a dropdown, or "combo box" control as a navigation tool.  In
one method, the user must press the form button to cause the browser to go
to the new destination, and in the other method, the "OnChange" javascript
event causes the choice to take effect as soon as the selection is made.

I am trying to assess whether using the OnChange event to activate dropdown
navigation controls is accessible or not.  According to Charles, Jaws users
often have problems with it.  

There is a work around: pressing "ALT-DownArrow" will produce the effect of
pressing the mouse button and holding it, and allow the user to subsequently
browse the dropdown with the arrow keys, without activating the OnChange
event.  Freedom Scientific says their users generally know this technique.
Is it true?  

Do other assistive tools have problems with the OnChange method of
activating dropdown navigation?

-----Original Message-----
From: Charles McCathieNevile [mailto:charles@w3.org]
Sent: Sunday, December 09, 2001 7:19 AM
To: David Woolley
Cc: w3c-wai-ig@w3.org; cturne@essex.ac.uk
Subject: Re: Fw: [webwatch] Fw: [htmldesigners] What's the difference

Yes, what happens for a mouse user is that they click on the box (equivalent
in explorer to alt-down arrow) and then scroll up und down the list until
they have selected the item tehy want, at which point they release.

Usually there is no visual difference - the following button is often
provided, but a javascript frees the user from having to click it.

I think that the problem is not with HTML, but with browsers that force an
onChange event to be fired when you try to select with the arrow keys,
instead of waiting for you to move out of the combobox before registering
whether you have changed the selected item.

I don't know how many browsers have this problem, although I have noted it
a common experience for users of Jaws with IE.


Charles McCN

On Sun, 9 Dec 2001, David Woolley wrote:

  > > kind of comboboxes which only activate when you press some button
  > after
  > > them, as opposed to the ones which activate as soon as you press
  > cursor
  > > down.  I mean what would a mouse-user do with these different kinds of

  This sounds like a case of Document Object Model (popularly called
  JavaScript) onchange events being used.  The change wouldn't be
  recognized until the mouse button was released.  It's not an HTML
  problem, but a designer problem (designing only for clicking with a

  Plain HTML will not do this.

Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409
134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1 617
258 5999
Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia
(or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex,
Received on Tuesday, 18 December 2001 16:42:40 UTC

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