In sequence diagrams I've just discovered the auto-activate and return functionality which should make my diagrams cleaner and less repetitive. In the meantime I've been using arrows in each direction and have been in the habit of colouring positive / negative responses to emphasise the result. Is there a syntax for the return statement which would allow the line to be coloured? ("return #color description" seems obvious but doesn't work)
@startuml
skinparam sequencearrowcolor #black
Alice -> Bob: Good Request
Alice <[#green]- Bob: Positive Response
Alice -> Bob: Bad Request
Alice <[#red]- Bob: Negative Response
...
Alice -> Bob ++: Good Request
return Positive Response
Alice -> Bob ++: Bad Request
return Negative Response
@enduml