a11y in Feisty testing by default

[Henrik Nilsen Omma]

Hello,

Upstream Gnome has been discussing switching on the AT-SPI accessibility 
framework by default in test builds of Gnome. The possibility of Ubuntu 
doing the same was raised at UDS.

Spec: https://wiki.ubuntu.com/Accessibility/Specs/ATSPItestingByDefault

Obviously a distro is a different beast than an unstable version of a 
desktop environment in that we may have a large number of users 
participating throughout the testing cycle (upgrading from Edgy to 
Feisty is easier than compiling Gnome from CVS). So we need to have a 
separate discussion about this in Ubuntu.

I raised the question at last week's distro meeting. Colin had two main 
concerns that I will return to here:

(a) if it's *too* broken it could seriously impede development

AT-SPI is not badly broken in that it causes major problems for the 
system. If it was that bad we should reconsider shipping it in main. 
However there are some known issues:

 * There have been some very noisy but fairly harmless bugs (#62446)
 * Running AT-SPI can cause crashes in other applications like 
OpenOffice (bug #35313)
 * With AT-SPI switched on the whole desktop is noticeably slower than 
normal

Of course these are precisely some of the things that we are trying to 
improved with this expanded focus on testing. The little bits of code 
cruft that cause all this should be easier to spot and fix with many 
more observers.

If an individual tester or developers finds the issues above to be too 
annoying for daily use then the features can easily be switched off. A 
personal setting will override the default. If it is felt that even that 
is too intrusive then we can always roll the patch out again after a 
week or two.


(b) how do we arrange to turn it off again for people who install 
milestone releases of feisty and then upgrade?

If I have understood the design of the proposed patch correctly then 
this is taken care of. See: http://bugzilla.gnome.org/show_bug.cgi?id=362457
A gconf schema change is made which turns  AT-SPI on by default unless 
the user has explicitly chosen otherwise AND is only triggered on odd 
version numbers of Gnome. So installing Feisty pre-beta with Gnome 2.17 
would leave AT-SPI on (unless switched off by the user) but upgrading to 
Gnome 2.18 would set the default value to off.

[the one hitch there is that someone who needs these features and 
installs Feisty without altering these settings will find AT-SPI being 
turned off towards the end of the testing period -- However, I expect 
the small group who falls into this category -- users of AT who use 
unstable software -- will be fairly well read up on the issue and will 
know how to deal with it].

Those proposing this change in upstream Gnome are hoping that it will 
eventually lead to AT-SPI being permanently switched on in all 
Gnome-based distributions. Personally I think we are still quite far 
from that change. Much more performance and stability work needs to be 
done and even then it is an open question whether we would ask our 
general users to let their RAM and CPU cycles be used by features they 
don't need. I'd personally like to see a dynamically loadable AT-SPI.

But that's for the future ... For now we should decide on the simple 
question of general testing of AT-SPI in Feisty unstable. I think it is 
reasonable to ask our testers and developers to try AT-SPI by default. 
This group likely has more beefy hardware and a higher tolerance for 
bugs than we can expect from our users.

Discuss.

Henrik