Tom, the answer is no. The hook on the Custom 400's door only holds it completely closed. It's all or nothing.
It's interesting that the Riviera seems to be the BOL model, yet has the partial door system for superior roasting. It also has the coil that cycles on and off depending on the heat setting. The 400's have coils that remain constantly lit, but with less intensity depending on the heat setting selected.
The Riviera also doesn't offer the baking tray option. Thus, the term "Bakes" is missing from the verbiage across the bottom of the window. On the 400's it reads, "Barbeques, Bakes, Broils, Roasts, Grills, Fries, Boils, Toasts"