Accessible Login in 12.04?

Luke Yelavich themuso at ubuntu.com
Fri Mar 16 02:14:25 UTC 2012


On Thu, Mar 15, 2012 at 08:16:01PM EST, Hammer Attila wrote:
> Hy,
> 
> I see happened an upgrade with Casper package, to migrate LightDm
> a11y settings with GSettings, because Unity Greeter using GSettings.
> 
> When I try use an installed system in terminal the sudo -u lightdm
> gsettings set com.canonical.unity-greeter screen-reader false
> command, I get following error:
> hammera at hammera-Satellite-L300:~$ sudo -u lightdm gsettings set
> com.canonical.unity-greeter screen-reader false
> 
> ** WARNING **: Command line `dbus-launch
> --autolaunch=57457bea3de3d18c6e5b50340000000d --binary-syntax
> --close-stderr' exited with non-zero exit status 1: No protocol
> specified\nNo protocol specified\nAutolaunch error: X11
> initialization failed.\n
> 
> ** WARNING **: Command line `dbus-launch
> --autolaunch=57457bea3de3d18c6e5b50340000000d --binary-syntax
> --close-stderr' exited with non-zero exit status 1: No protocol
> specified\nNo protocol specified\nAutolaunch error: X11
> initialization failed.\n
> hammera at hammera-Satellite-L300:~$

The reason why that doesn't work is due to the way gsettings works. Gsettings supports multiple backend data storage formats, one of which is dconf. Dconf is the default data storage format, which is a database stored at the system/user level. When gsettings wants to use dconf, it communicates via dbus to a dconf service process that runs as the user. This dconf service process makes the requested changes. So the above doesn't work, because there is no dconf service running as the lightdm user when you are logged into the system as another user.

> Look what the result if I run sudo -u lightdm gsettings get
> com.canonical.unity-greeter screen-reader command:
> hammera at hammera-Satellite-L300:~$ sudo -u lightdm gsettings get
> com.canonical.unity-greeter screen-reader
> false

I have seen this myself. I suspect either there is some caching going on somewhere, or the gsettings dconf backend can read the database itself, but cannot write.

> During installation this GSettings key with LightDm are setting properly?

Yes, when the screen reader profile is enabled, this key now gets set. That was one of the changes in the updated casper package.

> How can possible enable an installed Ubuntu 12.04 system the screen
> reader support in login screen if this error is present? Temporary
> need sighted assistance?

Control + S should work in the unity-greeter, however there are some weird focus issues when unity-greeter first loads, which for some reason prevent control + S from working. If you tab to the session selection box, and shift-tab back to the password prompt or login button, and then press Control + S, Orca should load. When you press Control + S, the screen reader will be active for every subsequent use of unity-greeter, until its turned off again.

Luke



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