Tk::IO is now layered on perls IO::Handle class. Interfaces
have changed, and are still evolving.
In theory C methods which enable non-blocking IO as in earlier Tk-b*
release(s) are still there. I have not changed them to use perls
additional Configure information, or tested them much.
Assumption is that <B>execB> is
used to fork a child process and a callback is called each time a
complete line arrives up the implied pipe.
line should probably be defined in terms of perls input record
separator but is not yet.
The -childcommand callback is called when end-of-file occurs.
$fh-><B>waitB> can be used to wait for child process while processing
other Tk events.
$fh-><B>killB> can be used to send signal to child process.