Hi,
I'm not sure what you mean by “cells", but I'm guessing you mean slots?
Slots - Spine User Guide
Currently, you can only create folders in the Tree view for animations, events, and skins, but not for bones and slots as you wrote. In Spine, things in the Tree view are called "items", and a common solution when there are too many items and it is difficult to see them is as follows:
・Use the Filter
The tree can be filtered to show only the chosen types of tree nodes. Please see this section of User Guide for more information:
Tree view - Spine User Guide: Filters
No keys are set by default, but you can edit hotkeys.txt to switch between tree filters by hotkeys.
・Use the Text search
The search box at the top of the tree allows items in the tree to be found by typing. If the Text search filters tree filter is active, only matching items are shown.
Tree view - Spine User Guide: Text search
Spine Tips: text search select
・Create bones as folders
This is not some special feature, but it is a method that many Spine animators practice. In general, bones are created to transform some attachments, but they can also be created just to organize the hierarchy of the Tree. Actually, having a few extra bones in the skeleton doesn't affect performance in the game that much.
If you want to create bones to organize the hierarchy, you may want to change the icon or uncheck Select:
Bones - Spine User Guide: Icon
Bones - Spine User Guide: Select
Also, you can use color tags for the Tree items. Please note color tags will also affect the name of the item at runtime, so you should not use it for items that you plan to manipulate in the game. However, you can use it for items that you just want to organize in the editor:
Spine Tips: tree bones colors
I hope these will help.
