Bug 296822 NullProgressMonitor is not thread safe for expected usage
NullProgressMonitor.setCanceled and isCanceled access the cancelled field, but there's no synchronization. The expected use is that setCanceled is called from a thread other than the one doing the work, which polls isCanceled(), so this needs to be thread safe. Could either make these two methods synchronized or make the field volatile. Should check other progress monitor implementations too.
bundles/org.eclipse.jface/src/org/eclipse/jface/action/StatusLine.java
layout();
		}
	}
	/**
	 * @private
	 */
	void startTask(final long timestamp, final boolean animated) {
		if (!fProgressIsVisible && fStartTime == timestamp) {
			showProgress();
			if (animated) {
				if (fProgressBar != null && !fProgressBar.isDisposed()) {
					fProgressBar.beginAnimatedTask();
				}
			}
		}
	}
	/**
	 * Notifies that a subtask of the main task is beginning. Subtasks are
	 * optional; the main task might not have subtasks.
	 * 
	 * @param name
	 *            the name (or description) of the subtask
	 * @see IProgressMonitor#subTask(String)
	 */
	public void subTask(String name) {
		String newName;
		if (name == null)
			newName = Util.ZERO_LENGTH_STRING;
		else
			newName = name;