Bug 174272 FileStoreEditorInput needs to be restorable
3.3 M5 The FileStoreEditorInput needs to restorable on startup. Therefore it needs to return an IPersistableElement and there needs to be an element factory.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDE.java
IFile file = ResourceUtil.getFile(saveable);
				if (file != null) {
					return isDescendantOfRoots(file);
				}
			}
			return false;
		}
		/**
		 * Return whether the given resource is either equal to or a descendant of
		 * one of the given roots.
		 * 
		 * @param roots the root resources
		 * @param resource the resource to be tested
		 * @return whether the given resource is either equal to or a descendant of
		 *         one of the given roots
		 */
		private boolean isDescendantOfRoots(IResource resource) {
			for (int l = 0; l < roots.length; l++) {
				IResource root = roots[l];
				if (root.getFullPath().isPrefixOf(resource.getFullPath())) {
					return true;
				}
			}
			return false;
		}
		
		/**
		 * Return whether the given dirty editor part is editing resources that are
		 * descendants of the given roots.
		 *