New lineEdit_ambient next to the host/connect row - type a value and
press Enter to send {"System": {"AmbientTemp": ...}}. The server now
has a recv handler for the System channel (previously send-only):
updates the real Pot's ambient temperature and, where the controller
has an internal model (Smith), its model Pots too (new
set_ambient_temperature() on TempControllerSmith), then echoes the new
value back so the status bar label and entry itself stay in sync.
jens
40cf4b69cc