important point

The shape key for the folder is the same shape key data as the normal shape key.
The data for the folder is stored in the vertex group options.

(Since it is a specification that custom properties cannot be added to the shape key, it is implemented like this)

List filters are not available

• 
  
• The Sort by Name option and the Folders feature in the search menu at the bottom of the list cannot coexist, so enabling them will ignore folding and sorting.

others

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• The batch move function within a folder is heavy when there are many items.
  • (Because the standard operator can only be used to sort the shape keys)