Bug 62401 [Actions] ReferenceCleanerThread in ActionContributionItem cause application can not exit normally.
When the standalone application exit, the display disposed, will call ReferenceCleanerThread.stopCleaning() method, it simply set the running field to false, but "reference = referenceQueue.remove();" in line 196 still blocking. And you must call System.exit() explicitlly to terminate the currently running Java Virtual Machine. so I think it is a bug. My env: XP home edition, jdk 1.4.2_04, and eclipse-SDK-I20040514-win32 Regards, Eric
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ActionContributionItem.java
return (Image) value;
            }
            
            final Image image = getImage(descriptor);
            if (image != null) {
                final Image greyImage = new Image(null, image, SWT.IMAGE_GRAY);
                greyMap.put(key, greyImage);
                return greyImage;
            }
            
            return null;
        }
        /**
         * Returns the regular image (i.e., enabled) for the given image
         * descriptor. This caches the result so that future attempts to get the
         * image for the same descriptor will only access the cache. When the
         * last reference to the image descriptor is dropped, the image will be
         * cleaned up. This clean up makes no time guarantees about how long
         * this will take.
         * 
         * @param descriptor
         *            The image descriptor for which an image should be created;
         *            may be <code>null</code>.
         * @return The image, either newly created or from the cache. This value
         *         is <code>null</code> if the parameter passed in is
         *         <code>null</code>.
         */
        private final Image getImage(final ImageDescriptor descriptor) {
            if (descriptor == null) { return null; }