Changing system time confuses timeouts

[Bill Wilson <billw wt net>]

I use a gtk_timeout_add() and my callback always returns TRUE so that
I can periodically update a scrolling set of charts.  When the system time
is changed back the timeout stops being called until the system time catches
up to the timeout trigger point.  If system time is set forward, the timeout
may also stop being called for a while.

I know why this is happening (expiration time is current time plus an interval),
but is there some way to set up a timeout so my callback will always be called
on schedule?  This is a problem when ntpdate periodically adjust the time.

---
Bill Wilson <billw@wt.net>