Another way to filter the dismissed items other than manual: Child->Dismissed. Note that "dismissed filter" is a superset of dismissed and done elements.
Nice ! I used this approach to mass delete all topics from wikipedia splitted articles: references, see also, further reading etc.
2:13 You might need to repeat the entire prodedure, in case some folders only contain an empty subfolder.
Btw I did something similar to apply templates to "No template" topics, and I had like 4.3K dismissed/done topics in my main collection. This grows slowly but steadily!
Come on! 3 years later and I was the only one to comment? Shocking!
@PleasurableLearning