We speak with Tudor about mixing layout, and here is something I try.

====================================

| view rawView |
rawView := ROView new.
view := ROMondrianViewBuilder view: rawView.
"-------------"
"-------------"

   view shape rectangle borderColor: (Color white).

   view nodes: ROObject withAllSubclasses forEach: [ :each |
               view nodes: each withAllSubclasses .
               view edgesFrom: #superclass.
               view layout: (ROTreeLayout new horizontalGap: 4) .
   ].

       view layout:( RORectanglePackingLayout new ratioWidth: 100 height: 100 ).

"-------------"
"-------------"
"Below is the initiation of the menu and opening the visualization"
ROEaselMorphic new populateMenuOn: view.
view open

=======================================

So, it seems it can be done with not too long a script.

Regards

Math