@Dave Jones the problem that you describe is almost certainly already reported as:
https://bugs.launchpad.net/unity/+bug/1305586 (Lock screen is unusable when some windows have a keyboard/mouse grab)
I also think that this bug is a duplicate of Bug #1305586.
@Dave Jones the problem that you describe is almost certainly already reported as:
https:/ /bugs.launchpad .net/unity/ +bug/1305586 (Lock screen is unusable when some windows have a keyboard/mouse grab)
I also think that this bug is a duplicate of Bug #1305586.