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<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width; initial-scale=1.0">
  <title>Dragging the mouse on a transformed scrollframe inside a fixed-pos element</title>
  <script type="application/javascript" src="apz_test_native_event_utils.js"></script>
  <script type="application/javascript" src="apz_test_utils.js"></script>
  <script src="/tests/SimpleTest/paint_listener.js"></script>
  <script type="text/javascript">
async function test() {
  var scrollableDiv = document.getElementById("scrollable");
  let scrollPromise = new Promise(resolve => {
    scrollableDiv.addEventListener("scroll", resolve, {once: true});
  });
  // Scroll down a small amount (10px). The bug in this case is that the
  // scrollthumb remains a little "above" where it's supposed to be, so if the
  // bug manifests here, then the thumb will remain at the top of the track
  // and the scroll position will remain at 0.
  var dragFinisher = await promiseVerticalScrollbarDrag(scrollableDiv, 10, 10);
  if (!dragFinisher) {
    ok(true, "No scrollbar, can't do this test");
    return;
  }
  // the events above might be stuck in APZ input queue for a bit until the
  // layer is activated, so we wait here until the scroll event listener is
  // triggered.
  await scrollPromise;
  await dragFinisher();
  // Flush everything just to be safe
  await promiseOnlyApzControllerFlushed();
  // In this case we just want to make sure the scroll position moved from 0
  // which indicates the thumb dragging worked properly.
  ok(scrollableDiv.scrollTop > 0, "Scrollbar drag resulted in a scroll position of " + scrollableDiv.scrollTop);
}
waitUntilApzStable()
.then(test)
.then(subtestDone, subtestFailed);
  </script>
  <style>
    #fixed {
      position: fixed;
      left: 0;
      top: 0;
      width: 300px;
      height: 100%;
    }
    #scrollable {
      transform: translateY(100px);
      overflow: scroll;
      height: 100%;
    }
    #content {
      height: 5000px;
      background-image: linear-gradient(red,blue);
    }
  </style>
</head>
<body>
<div id="fixed">
  <div id="scrollable">
    <div id="content"></div>
  </div>
</div>
</body>
</html>