SENTiNEL, Not with OD+. Not that I've see, anyway.
Stardock designed Dell's dock about 2 years ago. Though similar to ObjectDock, they designed it with features unique to itself. One such feature is the "categories" to which you refer.
From what I gather, categories may be a feature in ObjectDock 2.0 when it comes out, but it is not currently available for OD 1.91.
Maybe ask (pm) WebGizmos...he knows a heck of a lot more about OD than I do, and you could ask messiah1 who is also an OD skinner.
I think you forgot someone, Doc...