Hi Julian,

I went through your patch again and installed a slightly modified
version, mostly formatting issues (attached).  I guess you're now more
familiar than I am with specific pthread issues, so I could have missed
a few points.

You changed `all-threads' so that it hides the signal-delivery thread.
It seems harmless and reasonable, so I installed it too.  If others can
think of reasons not to do it, please speak up.

Thanks!

Ludovic.