Bug 33016 Show In...: "Package Explorer" is enabled when opening a file from cvs repository
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
implements ISetSelectionTarget, IMenuListener,
		IShowInTarget,
		IPackagesViewPart,  IPropertyChangeListener, 
		IViewPartInputProvider {
	
	private boolean fIsCurrentLayoutFlat; 
	private static final int HIERARCHICAL_LAYOUT= 0x1;
	private static final int FLAT_LAYOUT= 0x2;
	
	public final static String VIEW_ID= JavaUI.ID_PACKAGES;