Comment 17 for bug 857813

Works as intended on my fresh install. The toggle in preferences does turn it on and off in the unlock screen. Also Onboard shows up there right after its first launch.

Once it's in there, it doesn't go away on its own though. It's still in the lock screen when I turn off the osk in universal access settings. It can be turned off manually in preferences, but perhaps ultimately something other than Onboard should toggle the gsettings key "embedded-keyboard-enabled" in sync with "screen-keyboard-enabled"?