Hi m.Th.
It's very simple:
All I am asking is that some sort of category assignment panel be allowed to dock
inside the Info group. That way the user can toggle visibility of ALL the metadata panels (including categories) with the one toolbar "Info visibility" button.
IMO the Category Sets panel should never be subordinate to (i.e. contained in/by) the Navigation (aka "Data") panel group. It has
no navigation function, only assignment and presentation and therefore doesn't belong there. But regardless of that,
where that panel goes should be up to the user, yes? I want it (or some sort of category assignment tool)
inside the Info container.
With regard to the Category Sets panel itself:
Suffice it to say that horizontal rows of concatenated category words with no apparent organization do not an efficient UI make. The user will spend too much time scanning the lists looking for a word. Much faster to scan scrollable vertical lists with control over the sorting order. Sometimes screen real estate efficiency has to be subordinate to interaction efficiency.
I'll address improvements/redesign of the Category Sets panel in a separate post after I have made a mockup to illustrate my proposals.
No need for a separate "engine", just a better UI.