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
Control ctrl2= fViewer.getControl();
							if (ctrl2 != null && !ctrl2.isDisposed()) 
								fViewer.expandToLevel(type2, 1);
						}
					}); 
				}
			}
		} catch(JavaModelException e) {
			
		}
	}
	
	/**
	 * Returns the element contained in the EditorInput
	 */
	Object getElementOfInput(IEditorInput input) {
		if (input instanceof IClassFileEditorInput)
			return ((IClassFileEditorInput)input).getClassFile();
		else if (input instanceof IFileEditorInput)
			return ((IFileEditorInput)input).getFile();
		else if (input instanceof JarEntryEditorInput)
			return ((JarEntryEditorInput)input).getStorage();
		return null;
	}
	
	/**
 	 * Returns the Viewer.
 	 */
	TreeViewer getViewer() {
		return fViewer;