Bug 169591 [Common Navigator] Show In fails for editor inputs
The show(ShowInContext) method for CommonNavigator only considers the selection of the context. When Show In Project Explorer is performed from an editor, the selection is empty and the input is provided. Unfortunately, this is problematic, as the show-in target needs to adapt the input to an IFile so this will probably need to have some sort of extension so that the Project Explorer can plug-in the proper support.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonNavigator.java
public final void setLinkingEnabled(boolean toEnableLinking) {
		isLinkingEnabled = toEnableLinking;
		firePropertyChange(IS_LINKING_ENABLED_PROPERTY);
	}
	/**
	 * @return Whether linking the current selection with open editors is
	 *         enabled.
	 */
	public final boolean isLinkingEnabled() {
		return isLinkingEnabled;
	}
	/**
	 * <p>
	 * Provides access to the commonViewer used by the current CommonNavigator.
	 * The field will not be valid until after
	 * {@link #init(IViewSite, IMemento)}&nbsp;has been called by the
	 * Workbench.
	 * </p>
	 *  
	 * @return The (already created) instance of Common Viewer.
	 */
	public CommonViewer getCommonViewer() {
		return commonViewer;
	}
	/**
	 * @return The Navigator Content Service which populates this instance of
	 *         Common Navigator
	 */
	public INavigatorContentService getNavigatorContentService() {
		return getCommonViewer().getNavigatorContentService();