A pressure support device (50) such as, such a CPAP machine (50), is provided, which includes a housing (51), and a controller (64) enclosed by the housing (51). The controller (64) operates the CPAP machine (50) independently or in combination with an accessory (70) such as, for example and without limitation, a humidifier (70). A user interface (66) is operably (74) coupled to the controller (64) and includes a primary display (72), a secondary display (74) and a single control (76). The single control (76) is operable in a first mode of operation to adjust operating parameters of the CPAP machine (50), and in a second mode of operation to adjust operating parameters of the humidifier (70). The secondary display (74) preferably comprises a dead front (74), which is operational (e.g., without limitation, visible) only in the second mode of operation. A method of operating a pressure support device (50) is also disclosed.