I can reproduce it with ubuntu-touch/ubuntu-rtm/14.09-proposed using (roughly) the steps from comment #9 but not with vivid-proposed.
Maybe that's due to different versions of Qt as I cannot spot any relevant difference in that part of unity8 code (greeter and launcher).
Since we're about to move Vivid to stable, I guess it's not worth the effort of finding and backporting whatever fixed it?
I can reproduce it with ubuntu- touch/ubuntu- rtm/14. 09-proposed using (roughly) the steps from comment #9 but not with vivid-proposed.
Maybe that's due to different versions of Qt as I cannot spot any relevant difference in that part of unity8 code (greeter and launcher).
Since we're about to move Vivid to stable, I guess it's not worth the effort of finding and backporting whatever fixed it?