STR:
  - Go to https://mozilla.github.io/pdf.js/web/viewer.html
  - Click on "Open File" and open a pdf

The `Download` button and the `Current view` one just disappear.
I can reproduce this bug with Firefox nightly, Chrome stable and Epiphany on debian.
}
        handled = true;
        break;
      case 82: 
        PDFViewerApplication.rotatePages(-90);
        break;
    }
  }
  if (!handled && !isViewerInPresentationMode) {
    
    
    
    if (
      (evt.keyCode >= 33 && evt.keyCode <= 40) ||
      (evt.keyCode === 32 && curElementTagName !== "BUTTON")
    ) {
      ensureViewerFocused = true;
    }
  }
  if (ensureViewerFocused && !pdfViewer.containsElement(curElement)) {
    
    
    
    pdfViewer.focus();
  }
  if (handled) {
    evt.preventDefault();
  }
}
function beforeUnload(evt) {