1727936 - Touchpad scroll on Firefox window causes Firefox windows behind it to also scroll

Status: RESOLVED WORKSFORME

(Core :: Graphics: WebRender, defect)

Description

[Asif Youssuff]

If I have two Firefox windows open and overlapping (one in front of the other), scrolling the one in the foreground with my touchpad causes the window behind it to scroll as well.

Happy to provide further information.

Comment 1

[Asif Youssuff]

Attachment: about:support

Comment 2

[Jamie Nicol [:jnicol]]

Asif, does this only occur with gfx.webrender.compositor enabled? Could you try running mozregression if it's a recent issue?

Comment 3

[Asif Youssuff]

Jamie, this only happens when forcing the webrender compositor (gfx.webrender.compositor.force-enabled = true) and the issue is present since at least 2021-06-04, which is the first build I was able to find that wasn't basically unusable (the previous builds had flashing parts of windows).

Comment 4

[Jamie Nicol [:jnicol]]

Thanks Asif. Robert, can you reproduce this?

Comment 5

[Robert Mader [:rmader]]

Hm, no, can't reproduce. To me it also sounds like it's not a Firefox bug but rather a Mutter one:

• a Wayland surface only receives input events when it has an input region - and if it has, swallows them, so no other surface gets them.
• Wayland surfaces don't have an idea about their position, so Firefox/GTK doesn't know whether its windows overlap. If the issue only happens in overlapping areas (is that so?), then only the compositor would now about that area.

Comment 6

[Asif Youssuff]

Clicking rapidly on certain pages (I saw it on Jellyfin) also sometimes ends up with clicks "behind" the window I am clicking on, end up foregrounding another window.

Comment 7

[Robert Mader [:rmader]]

(In reply to Asif Youssuff from comment #6)

Clicking rapidly on certain pages (I saw it on Jellyfin) also sometimes ends up with clicks "behind" the window I am clicking on, end up foregrounding another window.

Yeah, I've seen that as well in other apps from time to time. For me this appears to have stopped in Gnome 41 (or locally applied pending MRs) in the Mutter picking code (which determines on what actor the cursor currently is). For now I'll assume this an external bug.

Comment 8

[Robert Mader [:rmader]]

Asif, can you still reproduce this?

Comment 9

[Asif Youssuff]

I haven't seen this issue in a while.

Comment 10

[Robert Mader [:rmader]]

Thanks, closing for now.