author Cosmin Sabou <>
Sun, 05 Feb 2023 19:37:33 +0000
changeset 651812 d8601249f1eb8c52c742b0c19c9ca0fa8f2e31fe
parent 581650 12cc3a6453674f034ff7737342622ecf90104c6f
permissions -rw-r--r--
Bug 1806090 - temporarily disable browser_quickactions.js on linux for frequent failures. r=intermittent-reviewers,MasterWayZ Differential Revision:

<meta charset="utf-8">
<meta name="viewport" content="width=device-width, minimum-scale=1.0">
<title>Tests scroll position is properly synchronized when visual position is temporarily clamped on the main thread</title>
<script src="apz_test_utils.js"></script>
<script src="/tests/SimpleTest/paint_listener.js"></script>
.hoverthingy, button {
    width: 100%;
    height: 200px;
    text-align: center;
    border: solid 1px black;
    background-color: white;

.hoverthingy:hover {
    background-color: lightgray;
<div id="filler" style="height: 5000px">This test runs automatically in automation. To run manually, follow the steps: 1. scroll all the way down</div>
<div class="hoverthingy">3. move the mouse. this div should have a hover effect exactly when the mouse is on top of it</div>
<button onclick="clampRestore()">2. click this button</div>
/* eslint-disable no-unused-vars */
function clampRestore() {
  // Shorten doc to clamp scroll position
  let filler = document.getElementById('filler'); = '4800px';
  // Force scroll position update
  let scrollPos = document.scrollingElement.scrollTop;
  // Restore height = '5000px';

function getAsyncScrollOffset() {
  let apzcTree = getLastApzcTree();
  let rcd = findRcdNode(apzcTree);
  if (rcd == null) {
    return {x: -1, y: -1};
  return parsePoint(rcd.asyncScrollOffset);

async function test() {
  document.scrollingElement.scrollTop = document.scrollingElement.scrollTopMax;
  await promiseApzFlushedRepaints();
  await promiseApzFlushedRepaints();
  let apzScrollOffset = getAsyncScrollOffset();
  dump(`Got apzScrollOffset ${JSON.stringify(apzScrollOffset)}\n`);
  // The bug this test is exercising resulted in a situation where the
  // main-thread scroll offset and the APZ scroll offset remained out of sync
  // while in the steady state. This resulted mouse hover effects and clicks
  // being offset from where the user visually saw the content/mouse. We
  // check to make sure the scroll offset is in sync to ensure the bug is fixed.
  is(apzScrollOffset.y, document.scrollingElement.scrollTop,
     "RCD y-scroll should match between APZ and main thread");

.then(subtestDone, subtestFailed);