3.7. User preferences
If the backend supports the USER_PREFERENCES server feature flag, the frontend will expect all the user’s preferences (default settings, color maps, interaction preferences and others) to be included in the REGISTER_VIEWER_ACK message. Changes to the user preferences can be made by the frontend through the SET_USER_PREFERENCES
control message. Each preference to be updated, along with the updated value, is stored as a map. User preference entries can be removed from the server by sending a SET_USER_PREFERENCES
message with a map of preference keys with empty values.
If the backend supports the USER_LAYOUTS server feature flag, the frontend will expect all the user’s custom UI layouts to be included in the REGISTER_VIEWER_ACK message. Changes to individual layouts (adding, updating or removing) are updated through the SET_USER_LAYOUT
control message.