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
* Collapse all. Collapses all expanded nodes.
	 * </p>
	 * <li>
	 * <p>
	 * Select Filters. Provides access to the "Select Filters" dialog that
	 * allows users to enable/disable filters and also the Content Extension
	 * activations.
	 * </p>
	 * </ul>
	 * 
	 * @return The Action Group to be associated with the Common Navigator View
	 *         Part.
	 */
	protected ActionGroup createCommonActionGroup() {
		return new CommonNavigatorActionGroup(this, commonViewer);
	}
	/**
	 * @return The initial input for the viewer. Defaults to
	 *         getSite().getPage().getInput()
	 */
	protected IAdaptable getInitialInput() {
		return getSite().getPage().getInput();
	}
	/**
	 * <p>
	 * Updates the title text and title tool tip. Called whenever the input of
	 * the viewer changes.
	 * </p>
	 */
	protected void updateTitle() {