Hello
"Bug", the next one: 
m=Mutex.new; m.synchronize { m.sleep }
fatal: No live threads left. Deadlock?
When doing it the first time (main thread), I get this error. (Ruby 2.6
- is it the same with 3.x?)
When doing it again (also with a new m!), then I don't get this failure:
m2=Mutex.new; m2.synchronize { m.sleep } # no error.
Which case is better (how to sleep for an event in the main-thread?)
In any case we should get the same behaviour when starting it the first
time, or later again...
Opti