default highlight all collections that contain the selected item like

remy_storage

Is there an option to default highlight all collections that contain the selected item like this https://www.zotero.org/support/kb/collections_containing_an_item

An error with a file is easily done.

Maybe is it possible to just create folder instead of collection (who is not my use-case) ?

LiborA

I think it is not a good idea. You can select more items and this function should be very source intensive. Also, if you select more items from different collections then the highlighting function is not working currently.