Bug 81877 Package explorer forgets active working set [package explorer]
3.1 M4 1. open pkg explorer. 2. select a working set, pkg explorer updates and filters out projects. 3. close pkg explorer. 4. open package explorer again and the working set is no longer applied. This used to work.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
return ((IJavaElement)element).getParent();
		else if (element instanceof IResource)
			return ((IResource)element).getParent();
			
		return null;
	}
	
	/**
	 * A compilation unit or class was expanded, expand
	 * the main type.  
	 */
	void expandMainType(Object element) {
		try {
			IType type= null;
			if (element instanceof ICompilationUnit) {
				ICompilationUnit cu= (ICompilationUnit)element;
				IType[] types= cu.getTypes();
				if (types.length > 0)
					type= types[0];
			}
			else if (element instanceof IClassFile) {
				IClassFile cf= (IClassFile)element;
				type= cf.getType();
			}			
			if (type != null) {
				final IType type2= type;
				Control ctrl= fViewer.getControl();
				if (ctrl != null && !ctrl.isDisposed()) {
					ctrl.getDisplay().asyncExec(new Runnable() {
						public void run() {