A pressure support device such as a CPAP machine, is provided, which includes a housing, and a controller enclosed by the housing. The controller operates the CPAP machine independently or in combination with an accessory such as, for example and without limitation, a humidifier. A user interface is operably coupled to the controller and includes a primary display, a secondary display and a single control. The single control is operable in a first mode of operation to adjust operating parameters of the CPAP machine, and in a second mode of operation to adjust operating parameters of the humidifier. The secondary display preferably comprises a dead front, which is operational (e.g., without limitation, visible) only in the second mode of operation. A method of operating a pressure support device is also disclosed.
