Thanks a lot for all the answers! Is there a place to look for "known issues"? This bug cost me many hours...
We want to avoid direct register access as often as possible. So we take the interrupt-workaround and wait for the bugfix in the next release.
By the way, why does the Synergy-configuration-tool allows symbolic names for every IO, but does not write them into a header-file? It would be so handy to name the IO “GPIO_LED_RED” in the configurator and use this directly in the call to pinWrite().
Regards
Volker