See also Orca bug #397680, which is blocked by this problem.
http://bugzilla.gnome.org/show_bug.cgi?id=397680

As reported by Krister on the Orca mailing list:

"I was trying to save a file in formated text format and wanted to edit
my ascii filter settings to make sure I could edit the file from
Windows, so I checked the "edit filter settings" check box in the "save
as" dialog in OpenOffice and pressed "OK". The edit filter settings came
up and I tried to choose the correct character set, namely Windows and
was surpriced when i couldn't see any character set at all. Pressing the
down arrow didn't produce neither speech nor braille. This has worked
before."

The problem is that there is another OOo dialog
coming up before the ASCII Filter Options dialog.

It's something like:

  This document may contain formatting or content that cannot be
  saved in the Text Encoded file format. Do you wish to save the
  document in this format anyway?

There are Yes and No buttons and a "Do not show this warning
again" checkbox.

Unfortunately the text for this dialog is not being spoken.
When it first comes up it just tells you the focus is on the
No button.

We investigated this problem. What we saw was that there is
single label on that dialog which has a LABEL_FOR relationship
with the "Yes" button. Neither the "Yes" button or the "No"
button have a LABELLED_BY relationship with that label.

In Orca, in speechgenerator.py, the _getSpeechForDialog() method calls
_getSpeechForAlert(), which in turn calls util.findUnrelatedLabels().
Because that label has a LABEL_FOR relationship, it's ignored.

Two possible solutions:

1/ Just remove the LABEL_FOR relationship from that label.
2/ Add LABELLED_BY relationships for the "Yes" and "No" buttons
   to that label.