title: Google Sheet - If tick a box, create a pop up message with button
body: <p>I am new to Google sheets. Previously, I have some C++ Background.</p>
  
  <p>I would like to write a custom code that performs the following:</p>
  
  <ol>
  <li>Tick the checkbox</li>
  <li>Confirmation message pops out</li>
  <li>Yes affirms the check, no unticks the box.</li>
  </ol>
  
  <p>In C, a function can only run once and it exits. How do I write a code in Google sheet whereby this code is constantly checking for the checkbox condition?</p>
  
  <p>Is there some kind of conditional script running?</p>