Unfortunately, disabling this completely breaks UI tests (in my case Java AssertJ Swing tests):
Caused by: java.awt.AWTException: java.awt.Robot requires your X server support the XTEST extension version 2.2
at sun.awt.X11.XRobotPeer.setup(Native Method)
at sun.awt.X11.XRobotPeer.<init>(XRobotPeer.java:51)
at sun.awt.X11.XToolkit.createRobot(XToolkit.java:958)
at java.awt.Robot.init(Robot.java:171)
at java.awt.Robot.<init>(Robot.java:164)
at org.assertj.swing.util.RobotFactory.newRobotInLeftScreen(RobotFactory.java:58)
at org.assertj.swing.image.ScreenshotTaker.<init>(ScreenshotTaker.java:66)
... 21 more