window resizing,
then fit &lt;F1&gt; for entering SngAmb mode.
 
  REPA updates the plot as soon as you hit the Central Mouse Button, but
it delays updating scratch file. It stores all entered commands in stack.
Any time  you can hit &lt;BackSpace&gt; it undoes the latest command and
decrement the stack counter. If you hit &lt;F10&gt; key, REPA will discard the
latest command in the stack without writing scratch files, leaves REPA and
returns to OPTIN. If you hit &lt;HOME&gt; REPA writes the scratch files, 