fixed-position-out-of-view-scroll-prepaint.html

<!DOCTYPE html>
<html>
<head>
  <style>
    body {
      height: 2000px;
      margin: 0px;
      padding: 0px;
    }
    .main {
      position: fixed;
    }
    .fixed {
      position: fixed;
      width: 100%;
      height: 100px;
      left: 0px;
      bottom: -100px;
      background-color: red;
    }
  </style>
</head>

<body>
  <div class="main">
    This test is applicable on platforms that do accelerated compositing, can prepaint out-of-view contents and can scroll the contents into the viewport without repainting them.<p>
    The following settings need to be enabled:<p>
    - preferCompositingToLCDTextEnabled<br>
    - fixedPositionCreatesStackingContext<p>
    To test, scroll the page up and down. The test passes if there is no temporary or permanent red in the page.
  </div>

  <!-- An out-of-view fixed element that should be never visible -->
  <div class="fixed"></div>
</body>
</html>

chromium/third_party/blink/manual_tests/compositing/fixed-position-out-of-view-scroll-prepaint.html