I find that seeing the dimmed content outside the frame is a distraction when trying to optimise the composition. There is currently no option to turn it off. Even when 'Capture outside the frame' is turned off in Camera > Settings the main screen still shows the dimmed content outside the frame.
I realise there is a valid argument that it can be useful to see what is just off the edge of the picture, (a claimed advantage of bright line viewfinders in rangefinders, but there is also an argument for seeing only what you are taking without distraction (advantage for SLRs).
The logical answer is not to show the area outside the frame if the setting is turned off.
Another factor is that the two features, Capture Outside and Deep Fusion, are mutually exclusive, which will tend to encourage switching Capture Outside on and off. The way it is currently designed means that there is no instant indication whether the Capture Outside setting (and hence Deep Fusion) is on or off. If the extra borders were not shown on the screen, there would be no doubt about whether Capture Outside (and hence Deep Fusion) setting was on or not.
I realise there is a valid argument that it can be useful to see what is just off the edge of the picture, (a claimed advantage of bright line viewfinders in rangefinders, but there is also an argument for seeing only what you are taking without distraction (advantage for SLRs).
The logical answer is not to show the area outside the frame if the setting is turned off.
Another factor is that the two features, Capture Outside and Deep Fusion, are mutually exclusive, which will tend to encourage switching Capture Outside on and off. The way it is currently designed means that there is no instant indication whether the Capture Outside setting (and hence Deep Fusion) is on or off. If the extra borders were not shown on the screen, there would be no doubt about whether Capture Outside (and hence Deep Fusion) setting was on or not.