input from custom device

["Boncek, John" <jboncek hunter com>]

We have a custom device with a small keypad and a numeric measurement
gadget.  I have successfully written code that checks for input from the
device's keypad in our idle loop and translates that into synthesized
key-press events to our top-level window.  So far, so good -- the
key-presses are working perfectly as input to the GUI.

I have also captured the numeric input in our idle loop when a measurement
is taken.  What is a good way to get the numeric measurement data to a GTK
window that needs it?  I've searched the archive of this list, the web,
the GTK tutorial, the GTK FAQ, and Havoc Pennington's book but found
nothing similar.  Pipes and sockets seem like they are for external input
from other processes, which is not the context here.  I would like the
input to go to a callback or something similar for the GUI code that
controls the windows but can't see a way to do it.