D&D a Button and a CheckBox
RMB on Button to select it and show contextual menu (leave menu open - do not select a menu item)
RMB on CheckBox - bug - Contextual Menu location moves to CheckBox but in fact the selection and CM is still associated with the Button.

This needs to work like Mac OS X Finder. Successive RMB should make a new selection and show the CM for the new selection. This is a viable workflow as a user may do successive RMB to explore contextual options on different nodes. The current behaviour is bad especially as the CM physically moves so it can fool the user into thinking the desired behaviour has happened.