As a followup, I ask that question because....
yEd has been running on my workstation since 2:22pm January 25, trying to build a graph from a GEDCOM file containing data on 32,180 people (this being a subset of a larger database containing over 48,000 people).
The program's window has blanked (black), but I can see its CPU usage and memory usage change (memory goes up close to 512mb, stays there for increasingly long periods of time, then drops back down).
I would like some confidence that it will eventually stop running, having either finished its task, or aborted. I *really* need to reboot the machine.