I can understand the need to use a pop up window with an error condition.
I would not subscribe to the need for knowledge about navigation in these
error situations.  Usually, the error condition is described in the
dialogue with only two options okay and details.  The dialogue needs to
explain how to address the problem as well.  If the user presses okay, the
browser would take you back to the problem application, hopefully placing
the user in the mistaken field or control.  I should say, not a problem as
long as the dialogue is more accessible than the Windows error dialogues
where you cannot read them a second time with your voice outputs reading
commands.  If the pop up or new window is to take you to a different web
page, there is a necessity to explain to the user before taking such new
window action.  My two cents, anyway.


At 12:48 PM 11/4/02 , you wrote:
>       Alan,
>
>       The big issue with pop-up windows (having been in this discussion
>in the W3C) is one of location and navigation. For "blind navigation,"
>the two important aspects are knowing where you currently are
>(location), and knowing how to get from where you are to where you want
>to be (navigation). Pop-up windows take the focus of the browser from
>the window where you think you are, and suddenly drop you into an
>unexpected place. The result is disorientation, and often a failure to
>provide navigation back to where you want to be.
>
>       Imagine that you are leaving your front door to go to work. You
>forgot your lunch on the kitchen counter, so your magic door decides
>that you should be back in the kitchen to get your lunch. It doesn't
>tell you that it's going to do this, just, boom, there you are.
>
>       As a sighted person, you would know that something odd had
>happened, because your refrigerator is not in your front yard.  But if
>it was the middle of the night, and this happened, you might crash into
>the refrigerator because you expected the sidewalk to your garage to be
>there.
>
>       You would be very disoriented, and have a difficult time figuring
>out what had happened.  Hence, pop-up windows (and magic doors) are bad
>things because then confuse both location and navigation.
>
>       Denis Anson, MS, OTR
>       Computer Access Specialist
>       College Misericordia
>       301 Lake St.
>       Dallas, PA 18612
>       email: [log in to unmask]
>       Phone: 570-674-6413
>
>
>       > -----Original Message-----
>       > From: * EASI: Equal Access to Software & Information
>       > [mailto:[log in to unmask]] On Behalf Of Alan Cantor
>       > Sent: Monday, November 04, 2002 1:41 PM
>       > To: [log in to unmask]
>       > Subject: What is the problem with accessible pop-up windows?
>       >
>       > I have a question about WCAG 1.0:
>       >
>       > 10.1: Until user agents allow users to turn off spawned
>windows, do
>       > not cause pop-up or other windows to appear and do not change
>the
>       > current window without informing the user.
>       >
>       > What problems are there with operating-system produced pop-up
>       > windows? Let's say a user enters data onto a form on a
>web-based
>       > application. The use hits the submit button, the data is
>validated,
>       > and is found to contain an error. If javascript pops an error
>       > message, there will be accessibility problems. But if Windows
>draws
>       > a dialog box to report the error (with an appropriate title
>bar,
>       > message text, and standard pushbuttons) is this a problem? What
>       > techniques are more accessible than an accessible pop-up
>window?
>       >
>       > Alan
>       >
>       >
>       > Alan Cantor
>       > Project Manager
>       > Strategic e-Government Implementation
>       > e-Government, OCCS
>       > 416-212-1152
>       > [log in to unmask]
>
---
Ross Eadie
Voice:  (204) 339-5287