title: What should go in a PDFTron custom script?
body: <p>PDFTron has the option to provide a custom Javascript file to modify the viewer, but I'm not sure what should go in this file, and I can't find any examples on the web.</p>
  
  <p>The website has the following description:</p>
  
  <blockquote>
    <p>Viewer Options - By default, PWS Cloud documents are loaded in a basic hosted version of WebViewer. You can customize the viewer's appearance, branding and custom features by loading an external JavaScript configuration file.</p>
  </blockquote>
  
  <p>When I supply this file, <strong>window.WebViewerUniversalInstance</strong> is null, and <strong>document.getElementById('DocumentViewer')</strong> returns a null object also.</p>
  
  <p>Can somebody point me in the right direction here, I'm lost.</p>
  
  <p>Thanks</p>