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

*** 188,201 ****
       * If false we operate in singleThreaded FX/AWT interop mode and nested loop uses NSDefaultRunLoopMode
       */
      private static final boolean inAWT;
  
      public LWCToolkit() {
!         areExtraMouseButtonsEnabled = Boolean.parseBoolean(System.getProperty("sun.awt.enableExtraMouseButtons", "true"));
          //set system property if not yet assigned
!         System.setProperty("sun.awt.enableExtraMouseButtons", ""+areExtraMouseButtonsEnabled);
!         initAppkit(ThreadGroupUtils.getRootThreadGroup(), GraphicsEnvironment.isHeadless());
      }
  
      /*
       * System colors with default initial values, overwritten by toolkit if system values differ and are available.
       */
--- 188,207 ----
       * If false we operate in singleThreaded FX/AWT interop mode and nested loop uses NSDefaultRunLoopMode
       */
      private static final boolean inAWT;
  
      public LWCToolkit() {
!         final String extraButtons = "sun.awt.enableExtraMouseButtons";
!         AccessController.doPrivileged((PrivilegedAction<Void>) () -> {
!             areExtraMouseButtonsEnabled =
!                  Boolean.parseBoolean(System.getProperty(extraButtons, "true"));
              //set system property if not yet assigned
!             System.setProperty(extraButtons, ""+areExtraMouseButtonsEnabled);
!             initAppkit(ThreadGroupUtils.getRootThreadGroup(),
!                        GraphicsEnvironment.isHeadless());
!             return null;
!         });
      }
  
      /*
       * System colors with default initial values, overwritten by toolkit if system values differ and are available.
       */