I would like to have the option to split the notes and attachments sections into two separate windows. Often, when taking notes, you have to juggle between the web browser (to open attachments externally) and the Brain. With this setup, you could stay entirely within Brain and continue taking notes without switching context.
I could even imagine having the attachments section overlay or replace the Plex side panel, allowing full-length display of the attachment while taking notes—all within the same application.

I believe this would improve the workflow.