To enhance a mono-output-only controller such as a mobile OS to support selective mono/stereo/mixed output, a stereo controller is instantiated in communication with the mono controller. The stereo controller coordinates stereo output, but calls and adapts functions already present in the mono controller for creating surface and image buffers, rendering, compositing, and/or merging. For content designated for 2D display, left and right surfaces are rendered from a mono perspective; for content designated for 3D display, left and right surfaces are rendered from left and right stereo perspectives, respectively. Some, all, or none of available content may be delivered to a stereo display in 3D, with a remainder delivered in 2D, and with comparable content still delivered in 2D to the mono display. The stereo controller is an add-on; the mono controller need not be replaced, removed, deactivated, or modified, facilitating transparency and backward compatibility.