src/java.desktop/share/classes/com/sun/java/swing/plaf/windows/AnimationController.java

*** 81,91 ****
      //this timer is used to cause repaint on animated components
      //30 repaints per second should give smooth animation affect
      private final javax.swing.Timer timer =
          new javax.swing.Timer(1000/30, this);
  
!     private static synchronized AnimationController getAnimationController() {
          AppContext appContext = AppContext.getAppContext();
          Object obj = appContext.get(ANIMATION_CONTROLLER_KEY);
          if (obj == null) {
              obj = new AnimationController();
              appContext.put(ANIMATION_CONTROLLER_KEY, obj);
--- 81,91 ----
      //this timer is used to cause repaint on animated components
      //30 repaints per second should give smooth animation affect
      private final javax.swing.Timer timer =
          new javax.swing.Timer(1000/30, this);
  
!     static synchronized AnimationController getAnimationController() {
          AppContext appContext = AppContext.getAppContext();
          Object obj = appContext.get(ANIMATION_CONTROLLER_KEY);
          if (obj == null) {
              obj = new AnimationController();
              appContext.put(ANIMATION_CONTROLLER_KEY, obj);
*** 202,212 ****
                                         State state) {
          component.putClientProperty(PartUIClientPropertyKey.getKey(part),
                                      state);
      }
  
!     private synchronized void startAnimation(JComponent component,
                                       Part part,
                                       State startState,
                                       State endState,
                                       long millis) {
          boolean isForwardAndReverse = false;
--- 202,212 ----
                                         State state) {
          component.putClientProperty(PartUIClientPropertyKey.getKey(part),
                                      state);
      }
  
!     synchronized void startAnimation(JComponent component,
                                       Part part,
                                       State startState,
                                       State endState,
                                       long millis) {
          boolean isForwardAndReverse = false;
*** 389,398 ****
--- 389,402 ----
                      alpha = progress;
                  } else {
                      alpha = 1 - progress;
                  }
                  g.setComposite(AlphaComposite.SrcOver.derive(alpha));
+                 if (state == null) { // used for animating buttons in a specific JToolBar
+                     g.setColor(Color.WHITE);
+                     g.fillRect(dx, dy, dw, dh);
+                 }
                  skin.paintSkinRaw(g, dx, dy, dw, dh, state);
                  g.dispose();
              } else {
                  skin.paintSkinRaw(_g, dx, dy, dw, dh, state);
              }