> Emacs on Windows can only monitor and kill its immediate subprocesses,
> it cannot monitor, let alone kill, any of their descendant processes,
> because it has no idea about them.  And the OS doesn't automatically
> kill all the processes in the subprocess tree, and there's no way to
> send a signal to them all, as on Posix platforms.  If killing the
> immediate child process doesn't cause some of its children to exit or
> abort, then those grandchildren will be left orphaned.

Windows NT does have the concept of parent processes, but an API call wasn't exposed in win32 until XP. I wrote a small patch that uses that and kills all child processes (as long as pid<0). I did some sanity testing and it works.

There are a few things that this patch leaves unaddressed:
- there is no error handling
- there is no OS detection - this will get ugly on Windows 9x and NT4/5.0
- performance: 3 API calls are made for each descendant process. This can be reduced to a total 3 calls (regardless of the child process count)

I'll fix these (and any other issues) if this fix is of any interest.