/**
* Filters out the tab descriptors that do not have any sections for the given input.
*/
protected List<FeaturePanelTabDescriptor> filterTabDescriptors(
List<FeaturePanelTabDescriptor> descriptors, IWorkbenchPart part, ISelection selection ) {
IFeatureSite site = toFeatureSite(selection);
if (site == null && part.getAdapter(IMap.class) != null) {
IMap map = (IMap) part.getAdapter(IMap.class);
site = new FeatureSiteImpl(map);
} else {
site = new FeatureSiteImpl(); // represents whatever is current?