1506197 - Incorrect scrollbar behavior with webrender

Status: RESOLVED DUPLICATE of bug 1501062

(Core :: Graphics: WebRender, defect)

Description

[Mark Macdonald]

Attachment: video showing the incorrect behavior

Name 	Firefox
Version 	64.0b7
Build ID 	20181105164654

1. While running webrender, load a page that requires vertical scrolling
2. Click and drag the scrollbar handle to scroll down
3. While still dragging, move the mouse cursor horizontally away from the scrollbar

Expected Result:
Scrollbar should "snap" back to its original position. (This is the native behavior on Windows)

Actual Result:
Scrollbar keeps tracking the cursor, no matter how far away the cursor gets.


Attached a video showing the incorrect behavior. Problem begins around 5s when the cursor moves away from the scrollbar -- expected the scrollbar to snap back to the top of the page, but it doesn't.


NOTE: If I go back to Direct3D (gfx.webrender.force-disabled = true), I see the correct behavior again.