src/java.desktop/macosx/native/libawt_lwawt/awt/AWTWindow.m

@@ -53,10 +53,15 @@
 // which had been the key window just before a new key window
 // was set. It would be nil if the new key window isn't an AWT
 // window or the app currently has no key window.
 static AWTWindow* lastKeyWindow = nil;
 
+// This variable contains coordinates of a window's top left
+// which was positioned via java.awt.Window.setLocationByPlatform.
+// It would be NSZeroPoint if 'Location by Platform' is not used.
+static NSPoint lastTopLeftPoint;
+
 // --------------------------------------------------------------
 // NSWindow/NSPanel descendants implementation
 #define AWT_NS_WINDOW_IMPLEMENTATION                            \
 - (id) initWithDelegate:(AWTWindow *)delegate                   \
               frameRect:(NSRect)contectRect                     \

@@ -1082,10 +1087,35 @@
     JNF_COCOA_EXIT(env);
 }
 
 /*
  * Class:     sun_lwawt_macosx_CPlatformWindow
+ * Method:    nativeSetNSWindowLocationByPlatform
+ * Signature: (J)V
+ */
+JNIEXPORT void JNICALL Java_sun_lwawt_macosx_CPlatformWindow_nativeSetNSWindowLocationByPlatform
+(JNIEnv *env, jclass clazz, jlong windowPtr)
+{
+    JNF_COCOA_ENTER(env);
+    
+    NSWindow *nsWindow = OBJC(windowPtr);
+    [ThreadUtilities performOnMainThreadWaiting:NO block:^(){
+        
+        if (NSEqualPoints(lastTopLeftPoint, NSZeroPoint)) {
+            // This is the first usage of lastTopLeftPoint. So invoke cascadeTopLeftFromPoint
+            // twice to avoid positioning the window's top left to zero-point, since it may
+            // cause negative user experience.
+            lastTopLeftPoint = [nsWindow cascadeTopLeftFromPoint:lastTopLeftPoint];
+        }
+        lastTopLeftPoint = [nsWindow cascadeTopLeftFromPoint:lastTopLeftPoint];
+    }];
+    
+    JNF_COCOA_EXIT(env);
+}
+
+/*
+ * Class:     sun_lwawt_macosx_CPlatformWindow
  * Method:    nativeSetNSWindowMinMax
  * Signature: (JDDDD)V
  */
 JNIEXPORT void JNICALL Java_sun_lwawt_macosx_CPlatformWindow_nativeSetNSWindowMinMax
 (JNIEnv *env, jclass clazz, jlong windowPtr, jdouble minW, jdouble minH, jdouble maxW, jdouble maxH)