Hi, A little workaround for: https://bugs.openjdk.java.net/browse/JDK-8256465
Calling: ObjCRuntime.disableAllowsAutomaticWindowTabbing() before first Window opens. It’s just a workaround, not a solution. Cheers Roger Tönz import java.util.logging.Level; import java.util.logging.Logger; import com.sun.jna.Library; import com.sun.jna.Native; import com.sun.jna.Pointer; public interface ObjCRuntime extends Library { Pointer objc_lookUpClass(final String className); Pointer sel_getUid(final String s); long objc_msgSend(final Pointer pointer, final Pointer selector, Object... args); private static long invoke(final String className, final String selectorN, Object... args){ final ObjCRuntime objCRuntime = Native.load("objc", ObjCRuntime.class); final Pointer clazz = objCRuntime.objc_lookUpClass(className); final Pointer selector = objCRuntime.sel_getUid(selectorN); return objCRuntime.objc_msgSend(clazz, selector, args); } //for MacOS 10.13 and higher (workaround for https://bugs.openjdk.java.net/browse/JDK-8256465) public static void disableAllowsAutomaticWindowTabbing() { try { ObjCRuntime.invoke("NSWindow", "setAllowsAutomaticWindowTabbing:", Boolean.FALSE); } catch(Throwable e){ Logger.getAnonymousLogger("ObjCRuntime").log(Level.WARNING, e, ()->"NSWindow#AllowsAutomaticWindowTabbing=???"); } } }