iOS screen mirroring shows overscan borders on selected apps

Problem: iPhone screen mirroring & a dedicated external view of my app show an inch of a black border on all sides.

But: Some views display perfect without black borders on the full-screen, e.g., the Apple TV menu and the photo app.

Tried already - with no effect:

• Disabled overscan on 1080p HD TV ("Disable 16:9 overscan") ( iPad Mirroring using 2 screens, does it support 1080 resolution? )
• set UIScreenOverscanCompensation - has no effect ( IOS - External (hdmi) output fills only half the screen except when coding view manually )

Setup: iPhone 4S (5.0.1), Apple TV 2nd generation (4.4.4)

Any suggestions what I could try additionally?

Ran into the same issue and it took a while to find the 'solution'. Turns out you can set the overscanCompensation to '3' and it will remove the borders.

I think Apple just left out the documentation & enum for UIScreenOverscanCompensationNone, but that down in the code they check for it.