Thanks minniepicker, yes, that is a possible workaround for my example, though I am hoping for more general hooks support.
on_delete: (when a file is deleted in the file browser, as I am trying to maintain an index of all my documents to enable faster searching, but I don't know when documents are deleted)
on_preview: so that small customisations can be made to the standard preview
My hope is that this would provide a mechanism for things to be "baked" into the UI, eg Global Search, but with that just being a hook to a standard workflow so it can be customised, etc
Obviously it ain't as easy as it sounds, but I can dream.