1. A method for drawing a polygon using a graphical user interface having a display of an object, the polygon in the form of a multitude of vertices and connecting lines forming a boundary around a region of interest in the object, wherein the display includes a fixed indicator superimposed on the object which is used to construct the vertices of the polygon, the method comprising the steps of (a) initially moving the object on the display so as to have the fixed indicator positioned relative to the object at a first location; (b) moving the object relative to the fixed indicator thereby creating a trail of vertices including a first vertex at the first location and a final vertex created at the completion of the moving step (b) and lines connecting the trail of vertices so as to form a portion of the boundary, wherein the portion of the boundary is displayed over the object, the boundary indicating the path of movement of the object relative to the fixed indicator; (c) activating a backstep function in which one or more previous vertices and connecting lines in the portion of the boundary are removed and the image is panned so that the fixed indicator is at the position last vertex in the trail of vertices; and (d) activating a user interface function indicating completion of the moving step (b), whereby the polygon is completed by connecting with a line the final vertex to the first vertex.