NVIDIA's Aaron Platner writes to the xorg-devel mailing list, "I'm trying to add support for overscan compensation to the Tegra X driver. This driver uses RandR 1.2, so I need to add an official mechanism for X clients to describe the desired configuration through the protocol."
NVIDIA is proposing that fields be added to DisplayModeRec for exposing horizontal and vertical borders to clients, a view-port rectangle attribute to the CRTC alongside the transform, a standardized property for outputs, or some other undecided change. Right now to provide RandR overscan compensation, Aaron is in support of adding a standardized property for the outputs as it would not require changing the Resize and Rotate protocol.
Regardless of the change, now that X.Org Server 1.11 is in a feature-freeze mode and has been branched, no RandR change will come before X.Org Server 1.12 in the next calendar year. Hopefully by then we will also have RandR 1.2+ support within NVIDIA's official (non-Tegra) proprietary driver.