Comment 16 for bug 1366534

Mmm, as the result of this, accessibility does not any more at all in lightdm. This is because setting NO_AT_BRIDGE to 1 would just completely disable accessibility, not only disabling autostart of at-spi-bus-launcher. This is thus not a proper solution. To summarize what we want:

- we need to kill the at-spi bus before starting the user session
- we don't want gtk-3 to auto-start at-spi-bus-launcher, since we wouldn't know how to kill it.
- we want accessibility to work in the gtk greeter.

So I propose the attached patch:

- if the at-spi command is not known, i.e. we assume that we don't know about accessibility, we don't know how to start it, so won't know how to kill it, so we set NO_AT_BRIDGE to 1 to make sure that gtk-3 won't unexpectedly load it either.
- if the at-spi command is known, we start the at-spi bus early, before any gtk initialization (which would auto-start the at-spi bus)

What do you think?