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
String text;
		if (fTaskName == null || fTaskName.length() == 0) {
			text = newName;
		} else {
			text = JFaceResources.format(
					"Set_SubTask", new Object[] { fTaskName, newName });
		}
		setMessage(text);
	}
	/**
	 * Trims the message to be displayable in the status line. This just pulls
	 * out the first line of the message. Allows null.
	 */
	String trim(String message) {
		if (message == null) {
			return null;
		}
		message = LegacyActionTools.escapeMnemonics(message);
		int cr = message.indexOf('\r');
		int lf = message.indexOf('\n');
		if (cr == -1 && lf == -1) {
			return message;
		}
		int len;
		if (cr == -1) {
			len = lf;
		} else if (lf == -1) {
			len = cr;
		} else {
			len = Math.min(cr, lf);