*precise* event times available? (for handwriting capture)

[John Ringland <ringland math buffalo edu>]

For an application that captures handwriting done
on a graphics tablet, I need *precise* motion-event timings.

Specifically, I need the motion-event times accurate to 1 millisecond
or better.

The times provided to my callback in the event->time field appear to 
be rounded to a multiple of 20 milliseconds, and are therefore much 
too coarse.

The function gettimeofday has sufficient resolution (microseconds), 
but must be called in the event callback at whatever time the
callback is called. And unfortunately, the motion events appear to 
be buffered, so that the motion event callback receives bursts of 
events: 3 to 5 events in a sub-millisecond interval, with about 20ms 
between bursts.

Thus neither of these approaches yield the time-resolution I need.

Is there another way?

Would it be possible and/or practical to alter code somewhere that
would allow storage of millisecond-accurate times in event->time?

Perhaps no-one has realized that timescales at or below 1 millisecond
are relevant for the user interface. In handwriting, they are! 

Any help greatly appreciated.

-John Ringland

PS In case it matters, my callback is registered like this:

gtk_signal_connect (GTK_OBJECT (drawing_area), "motion_notify_event",
		    (GtkSignalFunc) da_motion_classCallback, (gpointer)this );