[orca-list] The problem is "about: config"

[Max <heavy9922 gmail com>]

To reproduce the problem:

1. In the "firefox", go to "about: config";

2. Set the focus on the option "app.update.interval";

3. Press the shortcut menu, and select "change".

"Orca", while moving the cursor arrows, not to announce anything, so the 
current value, it is not possible to read. Also, "orca" did not announce 
the allocation, removal, and enter any character.
After pressing the "tab", and then "shift + tab" or vice versa, 
everything works fine.