What kind of UI design practices one could employ to protect the user's sensitive information from someone who might be looking (occasionally) at user's monitor from behind a shoulder or a nearby desk?
The software displays mostly a textual information and it is impossible for the user to use that software in a private space to avoid other's people watching.
What are the design decisions one could use to make it difficult for the onlooker to see what the user is reading or typing and to minimize the amount of information which could be "leaked" to other human eye?