As soon as there is contention for shared objects (e.g. public spray cans), then there is a need to regulate their access - floor control. There are different floor control strategies. For CSpray we provide both an explicit floor release mechanism and a time-out mechanism. That is, a request for a shared object can be met by an explicit release (e.g. button click) by the current floor holder, or after some period (e.g. 5-10 seconds) if there is no activity on the shared object. To show the users the different floor states of a shared object, we use the color scheme of a stop light. If the label of public spray can is red, then it is currently being used by someone else (the label is green for the person who owns the floor). When a request is made on a public can, the label of the can turns to yellow on all the participants indicating to the holder that someone wants it, and acknowledging the requester that the request was recognized.