I'm working on a project where I need to store some user-related config information in the database keyed off each Pane ID (pid). I could make a separate schema table for what I need to do, but I've noticed the presence of the 'extras' field and it would be perfect for my needs. It appears Panels doesn't use (or no longer uses?) this field - I can't find any piece of code that refers to it other than initializing it to an empty array when panes are created.

Would it be safe to use this field for app-specific data in the same way $user->data can be used? If this field is planned for some use or deprecated for removal, can this ticket be turned into a feature request to add a data field to panels_pane to replace it?