This add-on for the default WoW Professions UI was written because/due-to that the standard Professions UI doesn't remember what trees/categories were last opened or closed and when you're in and out of the profession for whatever reason(s), its annoying you have to search through them for what you wish to create or check what components are needed.
When first opened, the add-on will close all PRIMARY tree-categories, e.g. Outland Plans, Blacksmithing Plans (original vanilla), Kul Tiran Plans, and show you the skill-levels you have in each, e.g. 100/150, 99/300 or 122/175.
After this, whenever you open the profession's tab, it will remember and auto open/close tree-categories for whatever profession(s) you are viewing/using.
This currently works for all known professions, including the Junkyard Tinkering and Garrison system from Warlords of Draenor and Battle for Azeroth expansions.