I was able to reproduce this on the latest version of Ubuntu (15.10) by dragging a hyperlink from the browser to the edge of the screen, and then letting it go (it doesn't matter where). The launcher will then not reveal until <super> (or equivalent) is pressed. This isn't the only way to reproduce this, but it is the only one I have pinned down.
** Tags added: desktop-bugscrub-triaged -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1155598 Title: autohide launcher can be stuck hidden To manage notifications about this bug go to: https://bugs.launchpad.net/unity/+bug/1155598/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs