Hello. Please review fix for jdk11. Bug: https://bugs.openjdk.java.net/browse/JDK-8198335 Webrev can be found at: http://cr.openjdk.java.net/~serb/8198335/webrev.01
This bug cause the random failures of our headless tests. The reason is that we try to notify the GraphicsEnvironment(HeadlessGraphicsEnvironment), which does not implement DisplayChangedListener, about display change.
It is possible to skip this notification for headlesGE only, but I think that it is better to make instanceof before cast to DisplayChangedListener, usually we use this pattern in other places.
PS. Note that WToolkit.paletteChanged and WToolkit.displayChanged use different threads for notifications, I have created a bug to investigate this: https://bugs.openjdk.java.net/browse/JDK-8199881
-- Best regards, Sergey.
