Bug 263207 [CommonNavigator] Improve DnD tracing and add DnD test suite
There are no DnD tests for the Common Navigator. Also, the CNF has many test utility classes (basically stolen from JDT), these should be moved into a lower level area, and it looks like org.eclipse.ui.test.harness is a good place. (Perhaps we can get the JDT to use these identical versions as well so there is only one copy that everyone uses). Finally, the DnD tracing needs to be improved to show more information and show it more concisely.
tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/DisplayHelper.java
boolean events= false;
		if (display.sleep() && !timeoutState.hasTimedOut()) {
			driveEventQueue(display);
			events= true;
		}
		waiter.stop();
		return events;
	}
	
	/**
	 * The condition which has to be met in order for
	 * {@link #waitForCondition(Display, int)} to return before the timeout
	 * elapses.
	 * 
	 * @return <code>true</code> if the condition is met, <code>false</code>
	 *         if the event loop should be driven some more
	 */
	protected abstract boolean condition();
	/**
	 * Runs the event loop on the given display.
	 * 
	 * @param display the display
	 * @return if <code>display.readAndDispatch</code> returned
	 *         <code>true</code> at least once
	 */
	private static boolean driveEventQueue(Display display) {
		boolean events= false;
		while (display.readAndDispatch()) {
			events= true;
		}