Using Win32::GUI on Strawberry perl 5.16.2. According to the FAQ (http://perl-win32-gui.sourceforge.net/cgi-bin/docs.cgi?doc=userguide-faq) the way to have a long-running "background" process not block the GUI is to do a fork(), and have the child do the work.
I've tested this and it works, but I'm unclear about how to pass a message from the parent to the child in this situation. If I was on UNIX, I'd just do something like
kill USR1 $childpid
but this is Windows, not UNIX, and apparently the return value of fork() is a "pseudo-thread ID" which perlfork says can by used by kill() EXCEPT THAT "the signal will not be delivered while the pseudo-process is blocked by a system call". Well, it just so happens that the child's innermost loop is a select() statement, so from a practical standpoint the child has just shy of a snowball's chance of ever receiving the signal sent by kill (I tested it).
So my problem remains: given that fork() returns a "pseudo-thread ID" instead of a real PID or TID, how do I send a message from the parent to the child?