1. A man-machine interface method for permitting a user to act on thumbnails, each thumbnail representing an associated object containing information, for use with a machine having a video display device and a user input device, the man-machine interface method comprising: a) generating a three-dimensional environment, having a depth, to be rendered on the video display device; b) determining a two-dimensional location and a depth of each of the thumbnails in the three-dimensional environment, wherein, for each of the thumbnails, the depth is a function of at least one parameter of the object associated with the thumbnail; and c) generating the thumbnails within the three-dimensional environment, at the determined two-dimensional locations and depths, to be rendered on the video display device.