User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:81.0) Gecko/20100101 Firefox/81.0

Steps to reproduce:

I opened Firefox Nighly 81.0a1 (2020-8-21) on Wayland with either OpenGL or WebRenderer compositing in Plasma 5.19.4 in Fedora 33, with Qt 5.14.2, KF 5.73.0, mesa 20.1.6. I loaded a site. I right-clicked on the site multiple times. I loaded another site. I right-clicked on the back button multiple times.

Actual results:

The right-click pop-up menus over pages were flickering on most times when I moved the cursor over them. Multiple right-click menu entries were simultaneously highlighted blue in seemingly random and changing combinations as I moved the cursor over the menu. This problem occurred less frequently when I right-clicked on the back button. The problem happens with layers.acceleration.force-enabled=true in about:config to enable OpenGL compositing. The problem also occurs with WebRender compositing enabled with gfx.webrender.all true and gfx.webrender.enabled=true. This problem doesn't happen the same Nightly version on X. I tried to get a screenshot, but doing so caused the right-click menus to disappear.

Expected results:

The right-click menus would've appeared normally with just the menu entry under the cursor highlighted.

I have the same issue, Fedora 3 with KDE Plasma too on Wayland.
AMD GPU with Webrender enabled.

I've got a screenshot: https://imgpile.com/images/7135wx.png

I haven't been seeing this problem in Firefox Nightly 86.0a1 (2021-1-15) - 88.0a1 (2021-3-6) and 86.0 on Wayland with WebRender enabled in Fedora 34 with Plasma 5.21.2 and earlier due to the menu items under the cursor not usually being highlighted as I reported at https://bugzilla.mozilla.org/show_bug.cgi?id=1693472 The menus shown when right-clicking on an email item in a list of emails in Thunderbird 78.8.0 and earlier on Wayland flickered and had multiple simultaneously highlighted items when moving the cursor up and down them in Fedora 34 with Plasma 5.21.2 and earlier in the same way as I reported for FIrefox. This problem occurred in Thunderbird 78.8.0 on Wayland with OpenGL, WebRender, and in Safe mode with Basic compositing. Thunderbird on X hasn't had this problem. The underlying issue might be in kwin_wayland. I'm unsure if this a Plasma-specific problem as I've only had Plasma installed recently. Should I make a different report for this Thunderbird problem? Thanks.

I ran MOZ_ENABLE_WAYLAND=1 WAYLAND_DEBUG=1 thunderbird & I right-clicked on an email and saw the flickering and multiple highlighted menu items a few times. The attached Wayland debug log showed some repeated lines around when the problem happened like the following.

[1818472.163] wl_pointer@3.enter(1640, wl_surface@41, 599.000000, 695.000000)
[1818472.234] -> wl_pointer@3.set_cursor(1640, wl_surface@14, 4, 4)
[1818472.289] -> wl_surface@14.attach(wl_buffer@55, 0, 0)
[1818472.331] -> wl_surface@14.set_buffer_scale(1)
[1818472.356] -> wl_surface@14.damage(0, 0, 32, 32)
[1818472.408] -> wl_surface@14.commit()
[1818472.433] wl_pointer@3.frame()
[1818619.844] wl_pointer@3.motion(684063, 597.000000, 687.000000)
[1818619.934] wl_pointer@3.frame()
[1818619.979] wl_pointer@3.motion(684069, 593.000000, 677.000000)
[1818620.027] wl_pointer@3.frame()
[1818620.042] wl_pointer@3.motion(684077, 590.000000, 668.000000)
[1818620.058] wl_pointer@3.frame()
[1818620.068] wl_pointer@3.motion(684085, 587.000000, 659.000000)
[1818620.082] wl_pointer@3.frame()
[1818620.091] wl_pointer@3.motion(684093, 584.000000, 647.000000)
[1818620.105] wl_pointer@3.frame()
[1818620.116] wl_pointer@3.motion(684101, 581.000000, 633.000000)
[1818620.132] wl_pointer@3.frame()
[1818620.141] wl_pointer@3.motion(684109, 575.000000, 612.000000)
[1818620.178] wl_pointer@3.frame()
[1818620.190] wl_pointer@3.motion(684117, 569.000000, 595.000000)
[1818620.206] wl_pointer@3.frame()
[1818620.215] wl_pointer@3.motion(684125, 559.000000, 575.000000)
[1818620.229] wl_pointer@3.frame()
[1818620.238] wl_pointer@3.motion(684133, 549.000000, 555.000000)
[1818620.252] wl_pointer@3.frame()
[1818620.277] wl_pointer@3.motion(684141, 541.000000, 533.000000)
[1818620.291] wl_pointer@3.frame()
[1818620.320] wl_pointer@3.motion(684149, 533.000000, 509.000000)
[1818620.334] wl_pointer@3.frame()
[1818620.348] wl_pointer@3.motion(684155, 525.000000, 491.000000)
[1818620.363] wl_pointer@3.frame()
[1818620.375] wl_pointer@3.motion(684163, 521.000000, 471.000000)
[1818620.388] wl_pointer@3.frame()
[1818620.396] wl_pointer@3.motion(684171, 518.000000, 456.000000)
[1818620.410] wl_pointer@3.frame()
[1818620.423] wl_pointer@3.motion(684179, 514.000000, 440.000000)
[1818620.435] wl_pointer@3.frame()
[1818620.445] wl_pointer@3.motion(684187, 509.000000, 421.000000)
[1818620.459] wl_pointer@3.frame()
[1818620.471] wl_pointer@3.motion(684195, 505.000000, 402.000000)
[1818620.484] wl_pointer@3.frame()
[1818620.495] wl_pointer@3.motion(684203, 501.000000, 387.000000)
[1818620.508] wl_pointer@3.frame()
[1818658.219] wl_buffer@66.release()
[1818658.267] wl_callback@79.done(1638)
[1818658.290] wl_buffer@68.release()
[1818658.320] -> wl_buffer@68.destroy()
[1818663.311] -> wl_surface@49.attach(wl_buffer@66, 0, 0)
[1818663.408] -> wl_surface@49.damage(0, 0, 2147483647, 2147483647)
[1818663.447] -> wl_surface@49.commit()
[1818663.460] -> wl_display@1.sync(new id wl_callback@79)
[1818766.889] wl_display@1.delete_id(68)
[1818766.937] wl_display@1.delete_id(79)

The right-click menu problem happened a few times from around the lines above to the end.
I reported this issue at https://bugs.kde.org/show_bug.cgi?id=434115 and https://bugzilla.redhat.com/show_bug.cgi?id=1936224

I am also seeing this in Firefox with the Sway WM so I do not think it is unique to Plasma. Toolbar buttons and associated tooltips are also affected. I'm using Nightly 88.0a1 with Mesa 20.3.4 on Intel HD.

Now this has reached the stable version I notice it affects all menus and tooltips but only the first time they open. If you open a menu, close it and open it again, the flickering stops. Other GTK apps don't seem to be affected.

The same is going on for me.

OS: Debian bullseye
Firefox version: 87.0
sway: 1.5.1-2
Vídeo: Intel HD

And it is not only the first time I open the menu windows. For some extensions it happens all the time, for others it randomly happens.

Let me know if I can provide more info.

Same issue here as well.

Ubuntu Hirsute
Firefox 87.0
sway 1.5.1-2

I'm seeing the same issue on Gentoo, with Firefox 88.0 when using Sway.
The rate at which the menus flicker depends on mouse input. If I don't touch the mouse (or any other input, it's flickering in/out about every second (see attached video).
If I move the mouse, the flickering is a lot faster.
Also, if focus is moved to another window, the flickering immediately stops, with the menu becoming fully visible and usable.

Here's the WAYLAND_DEBUG=1 output that includes the part that happens when focus is moved to another window, what causes the flicker to stop immediately.
If I'm not mistaken, line 557 was when I moved the focus away from Firefox to the terminal window next to it.

This is not the log from the video before, but the same steps were taken:

1. launching Firefox in safe mode from terminal while having the mouse over the terminal
2. moving the mouse up so it's no longer on the terminal, but rather on the status bar
3. moving the mouse down, so it's on the terminal again, causing the focus to be moved from Firefox to the terminal

Hmmm, not sure if this is a Mozilla issue though. It seems that on Sway there is a fix on the compositor side.
I've tried the linked pull request on my local Sway install, and it seems to indeed fix the flickering of the menus/tooltips/etc.

https://www.reddit.com/r/swaywm/comments/mc04bj/psa_popup_menu_flickering_on_firefox_87_is_fixed/

Are you still experiencing the problem?
Determined whether it is a Sway bug?

(In reply to Wayne Mery (:wsmwk) from comment #11)

Are you still experiencing the problem?
Determined whether it is a Sway bug?

No, this problem hasn't been happening since Firefox Nightly 86.0a1 (2021-1-15) due to the menu items under the cursor not usually being highlighted which was fixed later at https://bugzilla.mozilla.org/show_bug.cgi?id=1693472 I haven't seen this problem in Thunderbird since the 91 stable branch was released. I saw the problem in Plasma. I haven't tried Sway.

Okay, closing then.
Thanks.