Bug 68011 [java search] "Search the JRE System Libraries" looks like a local preference but behaves as a global one... [search]
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/search/JavaSearchScopeFactory.java
private static JavaSearchScopeFactory fgInstance;
	private final IJavaSearchScope EMPTY_SCOPE= SearchEngine.createJavaSearchScope(new IJavaElement[] {});
	private final Set EMPTY_SET= new HashSet(0);
	
	private JavaSearchScopeFactory() {
	}
	public static JavaSearchScopeFactory getInstance() {
		if (fgInstance == null)
			fgInstance= new JavaSearchScopeFactory();
		return fgInstance;
	}
	public IWorkingSet[] queryWorkingSets() throws JavaModelException {
		Shell shell= JavaPlugin.getActiveWorkbenchShell();
		if (shell == null)
			return null;
		IWorkingSetSelectionDialog dialog= PlatformUI.getWorkbench().getWorkingSetManager().createWorkingSetSelectionDialog(shell, true);
		if (dialog.open() == Window.OK) {
			IWorkingSet[] workingSets= dialog.getSelection();