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
* necessary. Use caution when invoking this method as it can cause
	 * Navigator Content Extensions to load, thus causing plugin activation.
	 * </p>
	 * 
	 * @see org.eclipse.ui.part.ISetSelectionTarget#selectReveal(org.eclipse.jface.viewers.ISelection)
	 */
	public void selectReveal(ISelection selection) {
		if (commonViewer != null) {
			if(selection instanceof IStructuredSelection) {
				Object[] newSelection = ((IStructuredSelection)selection).toArray();
				Object[] expandedElements = commonViewer.getExpandedElements();
				Object[] newExpandedElements = new Object[newSelection.length + expandedElements.length];
				System.arraycopy(expandedElements, 0, newExpandedElements, 0, expandedElements.length);
				System.arraycopy(newSelection, 0, newExpandedElements, expandedElements.length, newSelection.length);
 				commonViewer.setExpandedElements(newExpandedElements);
			}
			commonViewer.setSelection(selection, true);
		}
	}
	/**
	 * <p>
	 * Linking is handled by an action which listens for
	 * changes to the {@link CommonNavigator#IS_LINKING_ENABLED_PROPERTY}.
	 * Custom implementations that wish to override this functionality, need to
	 * override the action used by the default ActionGroup and listen for
	 * changes to the above property.
	 * 
	 * @param toEnableLinking
	 *            True enables linking the current selection with open editors
	 */