To better support the idea of a block editor preview (distinct from a preview of the resulting rendered blocks) it might be worthwhile to consider supporting a flag on CK which would result in the hiding of + buttons for changing blocks and would set a disabled attribute on Fields. This setting would probably also have to be available to CK block definitions which would then have to honor the setting and disable any custom interactions that are present.
To better support the idea of a block editor preview (distinct from a preview of the resulting rendered blocks) it might be worthwhile to consider supporting a flag on CK which would result in the hiding of
+buttons for changing blocks and would set adisabledattribute onFields. This setting would probably also have to be available to CK block definitions which would then have to honor the setting and disable any custom interactions that are present.