See JDK-8013116 and correspondent regtest
The test fails after a change introduced in jdk9 b105. The robot moves mouse pointer not to the second screen NW corner + some 150 but to the far edge of the second screen.
It's not easy to reproduce the success since the current state of the test won't run without Jake M3 and too old won't compile because of the peer usage: try if you need some state circa b100.
Anyway, I tried and found the regression was in b105.