If you use GtkSocket/GtkPlug with multi-processes framework.
DON'T use function `forkProcess` to spawn process!

Because `forkProcess` just simple call C `fork`, haven't any protection,
then two processes will got *race condition*,
you will get X Window error (such as `BadWindow`) when those two processes
try to access same X resource.

So use `runProcess` or `runCommand` instead.
Above two functions add MVar lock when spawn processes (call c_runInteractiveProcess)
to make sure two processes won't get *race condition* problem on X resource.
