The tool supports searching for multiple hashtags, by entering e.g. HashtagA, HashtagB in the search box. The default behaviour as implemented is for this to return edits which contain either HashtagA or HashtagB. There are times, however, when a user might want to return results that contain HashtagA and HashtagB.
This could be implemented via a kind of Advanced Search dropdown. I wouldn't want to complicate the initially presented interface too much.