src/java.desktop/macosx/classes/sun/lwawt/macosx/LWCToolkit.java

*** 105,114 ****
--- 105,115 ----
  import sun.awt.CGraphicsDevice;
  import sun.awt.LightweightFrame;
  import sun.awt.PlatformGraphicsInfo;
  import sun.awt.SunToolkit;
  import sun.awt.datatransfer.DataTransferer;
+ import sun.awt.dnd.SunDragSourceContextPeer;
  import sun.awt.util.ThreadGroupUtils;
  import sun.java2d.opengl.OGLRenderQueue;
  import sun.lwawt.LWComponentPeer;
  import sun.lwawt.LWCursorManager;
  import sun.lwawt.LWToolkit;
*** 461,470 ****
--- 462,478 ----
          desktopProperties.put("DnD.Cursor.LinkNoDrop", new NamedCursor("DnD.Cursor.LinkNoDrop"));
      }
  
      @Override
      protected boolean syncNativeQueue(long timeout) {
+         if (SunDragSourceContextPeer.isDragDropInProgress()
+                 || EventQueue.isDispatchThread()) {
+             // The java code started the DnD, but the native drag may still not
+             // start, the last attempt to flush the native events,
+             // also do not block EDT for a long time
+             timeout = 50;
+         }
          return nativeSyncQueue(timeout);
      }
  
      @Override
      public native void beep();