Bug 214137 [Markers] Unbound system filters should be bound to problems view.
In 3.3 we supported systemFilters which are not currently picked up by the problems view. We should pick these up for compatiblity.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/views/markers/MarkerFieldFilterGroup.java
workingSetPaths = new HashSet();
			addResourcesAndChildrenPaths(getResourcesInWorkingSet());
		}
		return workingSetPaths;
	}
	/**
	 * Initialise the working set for the receiver. Use the window working set
	 * for the working set and set the scope to ON_WORKING_SET if they are to be
	 * used by default.
	 */
	private void initializeWorkingSet() {
		IWorkbenchWindow window = PlatformUI.getWorkbench()
				.getActiveWorkbenchWindow();
		if (window != null) {
			IWorkbenchPage page = window.getActivePage();
			if (page != null) {
				setWorkingSet(page.getAggregateWorkingSet());
				if ((PlatformUI.getPreferenceStore()
						.getBoolean(IWorkbenchPreferenceConstants.USE_WINDOW_WORKING_SET_BY_DEFAULT)))
					setScope(ON_WORKING_SET);
			}
		}
	}
	/**
	 * Return whether or not the receiver is enabled.
	 * 
	 * @return boolean
	 */
	public boolean isEnabled() {
		return enabled;