As implemented in SciTE these controls are evoked only if user provides calltip and auto-completion definitions (through *.api files) and user defines triggers for each action.
These can be seen as helpers at least in these scenarios:
- novice user learning SQL or PL/pgSQL - user learning PostgreSQL extension, like PostGIS - user manages own function
I attached screenshots of these suggestions as they appear in SciTE.
Sorry, I forgot to follow on this. This seems interesting. I'd love to see a patch for that :)