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<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");
// 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);
.then(subtestDone, subtestFailed);
#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);
<div id="fixed">
<div id="scrollable">
<div id="content"></div>