Bug 302791 [CommonNavigator] Associated editor does not close when deleting resource (editorInput) through CommonNavigator
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/NavigatorContentDescriptor.java
* @return True if and only if the extension might provide an object of this
	 *         type as a child.
	 */
	public boolean isPossibleChild(Object anElement) {
		if ((enablement == null && possibleChildren == null)
				|| anElement == null) {
			return false;
		} else if(anElement instanceof IStructuredSelection) {
			return arePossibleChildren((IStructuredSelection) anElement);
		}
		try {
			IEvaluationContext context = NavigatorPlugin.getEvalContext(anElement);
			if (possibleChildren != null) {
				return (possibleChildren.evaluate(context) == EvaluationResult.TRUE);
			} else if (enablement != null) {
				return (enablement.evaluate(context) == EvaluationResult.TRUE);
			}
		} catch (CoreException e) {
			NavigatorPlugin.logError(0, e.getMessage(), e);
		}
		return false;
	}
	
	/**
	 * A convenience method to check all elements in a selection.
	 * 
	 * @param aSelection A non-null selection
	 * @return True if and only if every element in the selection is a possible child.
	 */
	public boolean arePossibleChildren(IStructuredSelection aSelection) {