title: How to undo an action in gmsh
body: <p>I just connected two points with a straight line in gmsh, but how can I undo it ?</p>
  
  <p><a href="https://i.stack.imgur.com/4wNSg.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4wNSg.jpg" alt="enter image description here"></a></p>