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
if (button.getSelection() != bv)
						button.setSelection(bv);
				}
				return;
			}
		}
	}
	/**
	 * Updates the images for this action.
	 *
	 * @param forceImage <code>true</code> if some form of image is compulsory,
	 *  and <code>false</code> if it is acceptable for this item to have no image
	 * @return <code>true</code> if there are images for this action, <code>false</code> if not
	 */
	private boolean updateImages(boolean forceImage) {
		ImageCache cache = getImageCache();
		if (widget instanceof ToolItem) {
			if (USE_COLOR_ICONS) {
				Image image = cache.getImage(action.getHoverImageDescriptor());
				if (image == null) {
					image = cache.getImage(action.getImageDescriptor());
				}
				Image disabledImage = cache.getImage(action.getDisabledImageDescriptor());
				
				if (image == null && forceImage) {
					image = cache.getMissingImage();
				}
				
				if (disabledImage != null) {