title: How to set breakpoint on window close or prevent the Developer Tools window from closing?
body: <p>I opened the Developer Tools on a separate window for FireFox's pop-up window. The problem is that that pop-up window automatically closes by JavaScript after form submission and I cannot disable JavaScript itself because it needs JavaScript to submit the form.</p>
  
  <p>I searched for a way to disable automatic closing of the Developer Tools on window closing, and I found <a href="https://stackoverflow.com/questions/11136010/how-do-i-prevent-chrome-developer-tools-from-closing-when-the-current-browser-wi">this</a> but it was for Chrome. Typing <code>window.addEventListener('unload', function() { debugger; })</code> on the Console did not work. I could not find <code>Developer tools -&gt; "Sources" tab -&gt; Event Listener Breakpoints -&gt; Window -&gt; close</code> or <code>Event Listener Breakpoints -&gt; Load -&gt; unload</code>. The Event Listener Breakpoints panel has neither <code>close</code> nor <code>unload</code> (I typed them in the "Filter by event type").</p>
  
  <p>How can I prevent Developer Tools's separate window from closing?</p>