Maybe it was, that Lockscreen also accepts a numeric 0 instead of .F.

Every lockscreen = .t. increments an internal counter, and every lockscreen = .F. decrements it. Thus you really need to watch out to always have a balanced on/off couple count. You can override that with just setting that counter to 0, and don't care about "have I thought about every exit path in that module?"

That undocumented(?) feature is helpful if you're doing a lot of subroutines but don't know if everyone is behaving correctly