I and many others would appreciate having the option that when a new bookmark is created and added to a folder, it can be initially placed at the bottom of this folder (as is standard in other popular web browsers), rather than Opera's current behaviour of adding it to the top.
Would just be a simple option in settings that lets you switch between adding new bookmarks to the top or bottom of a folder, which I'd assume would be pretty easy to implement and wouldn't take much time.