I'm looking for Java bindings for XLib.
Specially, I need to be able to reparent an X windows application from within Java.
Ideally I would like to do this by making the X windows calls directly from java.
I don't know anything about XLib... but recently I ran across JNA and it seems that it can talk with system APIs so give it a look if you wish:
http://java-native-access.github.io/jna/4.4.0/javadoc/
Good Luck!