author Chris H-C <>
Fri, 22 Mar 2019 17:31:02 +0000
changeset 465740 c3d4eb5b3b2223aa6734bb8c2d39457ee768fc3c
parent 329664 7b434711753b98a87603453caaa0945791ffe12b
permissions -rw-r--r--
Bug 1536805 - Document Origin Telemetry r=janerik Differential Revision:

<!DOCTYPE html>
<html lang="en" class="reftest-wait">
<meta charset="utf-8">
<title>Starting to scroll the nested scrollbox shouldn't invalidate the fixed layer</title>


.content {
  box-sizing: border-box;
  width: 200px;
  height: 200px;
  border: 1px solid black;

.fixed {
  position: fixed;
  top: 20px;
  left: 240px;

.reftest-no-paint {
  border-color: lime;

.scrollable {
  overflow: auto;
  padding: 10px;

.scrolled {
  border: 1px solid gray;
  height: 400px;

body {
  margin: 0;
  padding: 20px;
  height: 3000px;


<div class="scrollable content" id="aboutToScroll">
    This scrollbox starts out without active scrolling and is going to become
    actively scrolled.
  <div class="scrolled"></div>

<div class="fixed reftest-no-paint content">
    This fixed layer gets its own PaintedLayer above the rest.
    When the contents of .scrollable require their own PaintedLayer, that
    should not cause .fixed to change layers.


function doTest() {
  document.querySelector("#aboutToScroll").scrollTop = 50 - document.querySelector("#aboutToScroll").scrollTop;
document.addEventListener("MozReftestInvalidate", doTest);