title: OpenLayers - lock rotation of box or rectangle geometry while modifying
body: <p>Openlayers provides useful functions for drawing boxes and rectangles and also has ol.geom.Geometry.prototype.rotate(angle, anchor) for rotating a geometry around a certain anchor. Is it possible to lock the rotation of a box/rectangle while modifying it?</p>
  
  <p>Using the OpenLayers example located <a href="http://openlayers.org/en/latest/examples/draw-shapes.html" rel="nofollow noreferrer">here</a> to draw a box with a certain rotation to illustrate the point:</p>
  
  <p><a href="https://i.stack.imgur.com/5fIJN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5fIJN.png" alt="Modifying a rotated box/rectangle polygon"></a></p>
  
  <p>I would like the box/rectangle to maintain its rotation while still being able to drag the sides longer and shorter. Is there a simple way to achieve this?</p>