rather than re-implementing 'windows' of notes, or using 'side-bars' for reading notes which take up screen real-estate, I propose being influenced by tiling window managers. Having an always-available 'workspace' for laying out a subset of notes, an always-available 'notebook' for searching your full note archives and then flexible, tiling spaces for seeing one, two or more note-texts in full next to each-other for reading or editing.