There items with works on all selected elements and items which applied to
element from which context menu was invoked by mouse.
For examople for two selected classes: 
- Edit|Delete; Resize To Context works for both
- Transform|To Actor,Show/Hide items,Select In Model,Compartment|Customize works
for "invoked" element only
Current behaviour inconsistant with GUI builder and as I remember with creator
behavior (where only common for all selected elemnts items are enabled).
It's unclear why I can't transform all classes to Actors or hide childs for all
selected classes.
It's good to have ability to customize compartments for all selected classes (of
cause only common part i.e. hide or show attributes and operations)