There may be a newer version with fixes, but I didn't see this mentioned in this forum:
In version 0.8.2, countdown to zero automatically restarts the countdown with no obvious way to stop first iteration.
Running a second instance of the app stops the first. E.g., 10 minutes countdown freezes at 9:13 with a second instance.
Trying to run it again, the app window flashes open briefly then closes. There is no obvious way to run pClock again after the crash.
Back to Android's timer. This is 32 Xenial.
@zigbert