This callback function is called when the workspace receives a PEN message from the DBS (or rather when we recieves an out of band data (OOB) on from the DBS).
With a NULL function value, restores the default handler in LIBLINCKS. The default call back function is installed in the library to handle the basic cases of notification described in section 7 and section 11.7.1. The high level interface to PEN is defined using a callback function on this level within LIBLINCKS.
The format of the PEN callback function is:
(*callback)(void *extra, int oob, int atoob);
where the argument have the following declaration and content:
The callback function is called from a unix signal handler and should thus be careful of which functions it calls in turn. See the man page for `signal(2)' for more information. It can set a flag which is checked in the application main loop or write a character on a pipe.