It is probably a bug in the Event.so shared library. In my experience, segmentation faults with Perl are almost always caused by C extension libraries.

One thing to check is the versions of the binary modules and the supporting libraries they use. What version of Perl/Tk are you using? Did you build the Tk module yourself or install a packaged distribution? Version mismatches between the module and the support library, and between Perl and the mdoule, always cause problems.