Bug 5774 Unpredicatable behaviour on double click in packages view
from EC: If you double click a file in the packages view, it opens the file (technically, compilation unit I believe) -- if not already open. However, if the file is already open, a single click selects it as the active editor tag; a double click expands its structure in the packages view. This is unpredictable behavior ;
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
import org.eclipse.jdt.internal.ui.IPreferencesConstants;
import org.eclipse.jdt.internal.ui.refactoring.actions.RefactoringAction;
import org.eclipse.jdt.internal.ui.refactoring.actions.RefactoringGroup;
import org.eclipse.jdt.internal.ui.actions.StructuredSelectionProvider;
import org.eclipse.jdt.internal.ui.reorg.DeleteAction;
import org.eclipse.jdt.internal.ui.reorg.ReorgGroup;
import org.eclipse.jdt.internal.ui.search.JavaSearchGroup;
import org.eclipse.jdt.internal.ui.util.JavaModelUtil;
import org.eclipse.jdt.internal.ui.util.OpenTypeHierarchyUtil;
import org.eclipse.jdt.internal.ui.viewsupport.JavaElementSorter;
import org.eclipse.jdt.internal.ui.viewsupport.MarkerErrorTickProvider;
import org.eclipse.jdt.internal.ui.viewsupport.ProblemTreeViewer;
import org.eclipse.jdt.internal.ui.viewsupport.StatusBarUpdater;
import org.eclipse.jdt.internal.ui.wizards.NewGroup;
import org.eclipse.jdt.ui.IContextMenuConstants;
import org.eclipse.jdt.ui.IPackagesViewPart;
import org.eclipse.jdt.ui.JavaElementContentProvider;
import org.eclipse.jdt.ui.JavaElementLabelProvider;
import org.eclipse.jdt.ui.JavaUI;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.IMenuListener;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.action.IStatusLineManager;
import org.eclipse.jface.action.IToolBarManager;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.action.Separator;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.jface.viewers.DecoratingLabelProvider;