RailwayRouteOptimization/scripts/Modify/Stretch/doc/Stretch_proc_en.html

<ol>
  <li>Choose in the options toolbar if you want to stretch a rectangular area
  (rectangle symbol) or a polygonal area (polygon symbol).</li>
  <li>Set the first corner of the stretch area.</li>
  <li>Set the second corner of the stretch area.</li>
  <li>For polygonal areas, set the other corners of the stretch area and
  right-click the last corner when finished.</li>
  <li>Set the reference point for moving using the mouse or enter a coordinate
  in the command line.</li>
  <li>Set the target point.</li>
</ol>