title: Prevent Google App script from executing in parallel
body: <p>I have a Google App script that is being executed by clicking on an floating image on a sheet.  </p>
  
  <p>How can I prevent people from running the script AGAIN before it is finished with the first execution?  </p>
  
  <p>It seems that you can execute the script multiple times by clicking the image and that the subsequent executions conflict with the previous ones and cause erroneous results.</p>
  
  <p>I was going to temporarily disassociate the script with the floating image while it is running an then restore it before exiting the script but I can't seem to find a way to manipulate the floating image's properties.</p>