In the Portfolio Editor, with this example:
Root
- Sub A
-- Sub A.1
-- Sub A.2
- Sub B
-- Sub B.1
-- Sub B.2
1) Select Sub B.1 in the left part of the Portfolio Editor
2) Right click Sub A -> Collapse All
--> On the left part of Portfolio Editor, the focus returns to Sub B.1. In the right part, the content of Sub A is displayed.