You may see a warning when starting an application (in this case
gedit) on DICE SL7:
** (gedit:26514): WARNING **: Couldn't register with accessibility bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
This warning is harmless. You can ignore it, or you can stop it happening by first typing the following command into your shell window:
To save you typing this, we’ve added it to DICE’s system-wide bash startup. It’ll be included in next week’s configuration update, which will hit machines on 4/5 November 2015.
As far as I can tell, the warning is produced when an application which uses GNOME’s GTK3 toolkit tries to connect to the GNOME Assistive Technology Service Provider Interface – which isn’t available, because SL7 DICE does not use GNOME’s own display manager, with which many core GNOME services are now integrated. Setting NO_AT_BRIDGE tells the application not to try to load the accessibility “bridge”.
This doesn’t seem to be mentioned in GNOME documentation. I did find a reference to it in the source of at-spi2-atk – “GTK+ module for bridging AT-SPI to ATK”. However I didn’t search the GNOME source exhaustively because, well, there’s a lot of it.
I’m sure it would be nice to be able to make use of whatever GNOME accessibility features are offered by GTK3, but since they seem to be inaccessible on systems which don’t use GDM for their login screens, we currently can’t. (We use lightdm instead of GDM.)
Edit: The story continues in part 2, Those accessibility warnings again.