The NamespaceManager class has several methods for selecting a list of topic names returned in the form of a QualifiedTopicNameCollection. All the various methods eventually call into

 NamespaceManager.AllTopics(ImportPolicy importPolicy, 
                                    Comparison<QualifiedTopicName> sortCriterion)

to do the work. I've modified this method to allow the filtering of the topics selected, so the worker method now looks like this

 NamespaceManager.AllTopics(ImportPolicy importPolicy, 
                                    Comparison<QualifiedTopicName> sortCriterion)
                                    Predicate<QualifiedTopicName> selectionCriterion)

Now, the behavior is that the results of the query into the ContentProviderChain is filtered based on the selectionCriterion before being sorted with the sortCriterion. This order of operations allow the potentially expensive Sort to be done on the exact set of topics desired instead of doing the sort first and then looking for the desired topics.

The method NamespaceManager.AllTopicsWith has been modified to get its list of QualifiedTopicNames using this mechanism.

Here is an example that looks for the topics that have a name that starts with "Foo"

 QualifiedTopicNameCollection topics;
 topics = namespace.AllTopicsSortedLastModifiedDescending(delegate(QualifiedTopicName name)
    {
       return name.LocalName.StartsWith("Foo");
    });