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.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IPath;
import org.eclipse.jdt.core.IClassFile;
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaModel;
import org.eclipse.jdt.core.IMember;
import org.eclipse.jdt.core.IOpenable;
import org.eclipse.jdt.core.ISourceReference;
import org.eclipse.jdt.core.IType;
import org.eclipse.jdt.core.IWorkingCopy;
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.internal.ui.IJavaHelpContextIds;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.actions.ContextMenuGroup;
import org.eclipse.jdt.internal.ui.compare.JavaAddElementFromHistory;
import org.eclipse.jdt.internal.ui.compare.JavaReplaceWithEditionAction;
import org.eclipse.jdt.internal.ui.dnd.DelegatingDragAdapter;
import org.eclipse.jdt.internal.ui.dnd.DelegatingDropAdapter;
import org.eclipse.jdt.internal.ui.dnd.LocalSelectionTransfer;
import org.eclipse.jdt.internal.ui.dnd.TransferDragSourceListener;
import org.eclipse.jdt.internal.ui.dnd.TransferDropTargetListener;
import org.eclipse.jdt.internal.ui.javaeditor.IClassFileEditorInput;
import org.eclipse.jdt.internal.ui.javaeditor.EditorUtility;
import org.eclipse.jdt.internal.ui.javaeditor.JarEntryEditorInput;
import org.eclipse.jdt.internal.ui.preferences.JavaBasePreferencePage;