Bug 81426 Package Explorer shows nothing after drill into working set, then show projects
I200412160800 - switch Package Explorer to working sets - context menu > Go Into a working set - Show > Projects -> view is empty -> view toolbar button 'Up to Working Sets' does not do anything
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
import org.eclipse.jdt.internal.ui.dnd.DelegatingDropAdapter;
import org.eclipse.jdt.internal.ui.dnd.JdtViewerDragAdapter;
import org.eclipse.jdt.internal.ui.dnd.ResourceTransferDragAdapter;
import org.eclipse.jdt.internal.ui.filters.OutputFolderFilter;
import org.eclipse.jdt.internal.ui.javaeditor.EditorUtility;
import org.eclipse.jdt.internal.ui.javaeditor.IClassFileEditorInput;
import org.eclipse.jdt.internal.ui.javaeditor.JarEntryEditorInput;
import org.eclipse.jdt.internal.ui.preferences.MembersOrderPreferenceCache;
import org.eclipse.jdt.internal.ui.util.JavaUIHelp;
import org.eclipse.jdt.internal.ui.viewsupport.AppearanceAwareLabelProvider;
import org.eclipse.jdt.internal.ui.viewsupport.DecoratingJavaLabelProvider;
import org.eclipse.jdt.internal.ui.viewsupport.FilterUpdater;
import org.eclipse.jdt.internal.ui.viewsupport.IViewPartInputProvider;
import org.eclipse.jdt.internal.ui.viewsupport.JavaElementImageProvider;
import org.eclipse.jdt.internal.ui.viewsupport.ProblemTreeViewer;
import org.eclipse.jdt.internal.ui.viewsupport.StatusBarUpdater;
import org.eclipse.jdt.internal.ui.workingsets.ConfigureWorkingSetAction;
import org.eclipse.jdt.internal.ui.workingsets.HistoryWorkingSetUpdater;
import org.eclipse.jdt.internal.ui.workingsets.ViewActionGroup;
import org.eclipse.jdt.internal.ui.workingsets.WorkingSetFilterActionGroup;
import org.eclipse.jdt.internal.ui.workingsets.WorkingSetModel;
 
/**
 * The ViewPart for the ProjectExplorer. It listens to part activation events.
 * When selection linking with the editor is enabled the view selection tracks
 * the active editor page. Similarly when a resource is selected in the packages
 * view the corresponding editor is activated. 
 */
 
public class PackageExplorerPart extends ViewPart