Bug 81099 JUnit preference does not Restore Defaults [JUnit]
I200412142000 Restore Defaults has no effect on the "Show JUnit view only when error occurs" preference.
org.eclipse.jdt.junit.core/src/org/eclipse/jdt/internal/junit/JUnitCorePlugin.java
* so that we only attach a TestRunner once to a launch.
	 * Once a test runner is connected it is removed from the set.
	 */
	private AbstractSet fTrackedLaunches= new HashSet(20);
	/**
	 * List storing the registered test run listeners
	 */
	private List fTestRunListeners;
	/**
	 * List storing the registered JUnit launch configuration types
	 */
	private List fJUnitLaunchConfigTypeIDs;
	private static boolean fIsStopped= false;
	public JUnitPlugin() {
		fgPlugin= this;
		String pathSuffix= "icons/full/"; 
		try {
			fgIconBaseURL= new URL(Platform.getBundle(PLUGIN_ID).getEntry("/"), pathSuffix); 
		} catch (MalformedURLException e) {
			
		}
	}
	
	public static JUnitPlugin getDefault() {
		return fgPlugin;
	}
	public static Shell getActiveWorkbenchShell() {
		IWorkbenchWindow workBenchWindow= getActiveWorkbenchWindow();
		if (workBenchWindow == null)
			return null;