src/macosx/classes/sun/lwawt/LWWindowPeer.java

*** 79,91 ****
      private volatile int windowState = Frame.NORMAL;
  
      // check that the mouse is over the window
      private volatile boolean isMouseOver = false;
  
      // A peer where the last mouse event came to. Used by cursor manager to
      // find the component under cursor
!     private static volatile LWComponentPeer lastCommonMouseEventPeer = null;
  
      // A peer where the last mouse event came to. Used to generate
      // MOUSE_ENTERED/EXITED notifications
      private volatile LWComponentPeer lastMouseEventPeer;
  
--- 79,92 ----
      private volatile int windowState = Frame.NORMAL;
  
      // check that the mouse is over the window
      private volatile boolean isMouseOver = false;
  
+     private static final Object lastCommonMouseEventPeerLock = new Object();
      // A peer where the last mouse event came to. Used by cursor manager to
      // find the component under cursor
!     private static LWComponentPeer lastCommonMouseEventPeer = null;
  
      // A peer where the last mouse event came to. Used to generate
      // MOUSE_ENTERED/EXITED notifications
      private volatile LWComponentPeer lastMouseEventPeer;
  
*** 708,720 ****
                  }
  
                  // Sometimes we may get MOUSE_EXITED after lastCommonMouseEventPeer is switched
                  // to a peer from another window. So we must first check if this peer is
                  // the same as lastWindowPeer
!                 if (lastCommonMouseEventPeer != null && lastCommonMouseEventPeer.getWindowPeerOrSelf() == this) {
!                     lastCommonMouseEventPeer = null;
!                 }
                  lastMouseEventPeer = null;
              }
          } else if(id == MouseEvent.MOUSE_ENTERED) {
              isMouseOver = true;
              if (targetPeer != null) {
--- 709,719 ----
                  }
  
                  // Sometimes we may get MOUSE_EXITED after lastCommonMouseEventPeer is switched
                  // to a peer from another window. So we must first check if this peer is
                  // the same as lastWindowPeer
!                 cleanLastCommonMouseEventPeer(this);
                  lastMouseEventPeer = null;
              }
          } else if(id == MouseEvent.MOUSE_ENTERED) {
              isMouseOver = true;
              if (targetPeer != null) {
*** 722,732 ****
                      Point lp = targetPeer.windowToLocal(x, y, this);
                      Component target = targetPeer.getTarget();
                      postMouseEnteredEvent(target, when, modifiers, lp,
                              screenX, screenY, clickCount, popupTrigger, button);
                  }
!                 lastCommonMouseEventPeer = targetPeer;
                  lastMouseEventPeer = targetPeer;
              }
          } else {
              PlatformWindow topmostPlatforWindow =
                      platformWindow.getTopmostPlatformWindowUnderMouse();
--- 721,731 ----
                      Point lp = targetPeer.windowToLocal(x, y, this);
                      Component target = targetPeer.getTarget();
                      postMouseEnteredEvent(target, when, modifiers, lp,
                              screenX, screenY, clickCount, popupTrigger, button);
                  }
!                 setLastCommonMouseEventPeer(targetPeer);
                  lastMouseEventPeer = targetPeer;
              }
          } else {
              PlatformWindow topmostPlatforWindow =
                      platformWindow.getTopmostPlatformWindowUnderMouse();
*** 851,861 ****
              Point oldp = lastMouseEventPeer.windowToLocal(x, y, this);
              Component target = lastMouseEventPeer.getTarget();
              postMouseExitedEvent(target, when, modifiers, oldp, screenX, screenY,
                      clickCount, popupTrigger, button);
          }
!         lastCommonMouseEventPeer = targetPeer;
          lastMouseEventPeer = targetPeer;
  
          // Generate Mouse Enter for components
          if (targetPeer != null && targetPeer.isEnabled()) {
              Point newp = targetPeer.windowToLocal(x, y, this);
--- 850,860 ----
              Point oldp = lastMouseEventPeer.windowToLocal(x, y, this);
              Component target = lastMouseEventPeer.getTarget();
              postMouseExitedEvent(target, when, modifiers, oldp, screenX, screenY,
                      clickCount, popupTrigger, button);
          }
!         setLastCommonMouseEventPeer(targetPeer);
          lastMouseEventPeer = targetPeer;
  
          // Generate Mouse Enter for components
          if (targetPeer != null && targetPeer.isEnabled()) {
              Point newp = targetPeer.windowToLocal(x, y, this);
*** 1109,1124 ****
--- 1108,1143 ----
          }
          return true;
      }
  
      public static LWWindowPeer getWindowUnderCursor() {
+         synchronized (lastCommonMouseEventPeerLock) {
              return lastCommonMouseEventPeer != null ? lastCommonMouseEventPeer.getWindowPeerOrSelf() : null;
          }
+     }
  
      public static LWComponentPeer<?, ?> getPeerUnderCursor() {
+         synchronized (lastCommonMouseEventPeerLock) {
              return lastCommonMouseEventPeer;
          }
+     }
+ 
+     static boolean cleanLastCommonMouseEventPeer(LWWindowPeer previous) {
+         synchronized (lastCommonMouseEventPeerLock) {
+             if (lastCommonMouseEventPeer != null && lastCommonMouseEventPeer.getWindowPeerOrSelf() == previous) {
+                 lastCommonMouseEventPeer = null;
+                 return true;
+             }
+             return false;
+         }
+     }
+ 
+     static void setLastCommonMouseEventPeer(LWComponentPeer<?, ?> newValue) {
+         synchronized (lastCommonMouseEventPeerLock) {
+             lastCommonMouseEventPeer = newValue;
+         }
+     }
  
      /*
       * Requests platform to set native focus on a frame/dialog.
       * In case of a simple window, triggers appropriate java focus change.
       */