In the media manager it is currently not possible to upload media files to a (new) namespace that isn't listed in the media manager when you don't have upload permissions for a parent/ancestor namespace of this (new) namespace.
I propose to add a namespace input in the namespace tree so you can open arbitrary namespaces and then upload files in this namespace as it is also not very obvious that you can enter a full id in the filename input.
This is the same as
https://github.com/akate/dokuwiki/issues/60