1. A method for stereo gaze tracking, the method comprising: tracking, with a tracking system having a single-eye tracker, a gaze point of a first eye of a user on a first one of right and left two-dimensional display screens of a stereo viewer, wherein the right and left two-dimensional display screens respectively display information of right and left stereo images of a scene captured by a stereoscopic camera, wherein the right and left two-dimensional display screens are visible to the user through right and left eyepieces, respectively; and estimating, by a processor, a gaze point of a second eye of the user on a second one of the right and left two-dimensional display screens by processing information, received from the tracking system, describing the tracked gaze point of the first eye only and information of the right and left stereo images of the scene.