Created attachment 180104 [details] Showcase of the bug. SUMMARY I initially reported this on virt-viewer GitLab, but I'm unable to reproduce it on Gnome. (https://gitlab.com/virt-viewer/virt-viewer/-/issues/161) When scrolling in the virt-viewer, every second scroll input in the same direction is doubled. STEPS TO REPRODUCE 1. Create a Linux VM in virt-manager. 2. Open a web browser. 3. Scroll in the same direction. OBSERVED RESULT Every other scroll in the same direction, is doubled. EXPECTED RESULT It should only send one scroll input. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 41 KDE Plasma Version: 6.3.4 KDE Frameworks Version: 6.12.0 Qt Version: 6.8.2 ADDITIONAL INFORMATION This bug also affects connections to the VM using different clients, such as Remmina. Oddly enough, Moonlight doesn't appear to be affected. Workaround for this bug: - Launch virt-manager/virt-viewer with GDK_BACKEND=x11. - Use 'Redirect USB Device' for the mouse in virt-viewer, but this makes the cursor invisible.
Do you have a non-default scroll speed configured in system settings?
(In reply to Zamundaaa from comment #1) > Do you have a non-default scroll speed configured in system settings? I'm using the default scroll speed settings, this bug also happens on a clean install of Fedora 41. I've also tried several input devices in case it was the hardware to blame: - Ploopy Adept (QMK, wired) - Kesington Slimblade Pro (USB, wired and dongle) - Pulsar Xlite V2 (Dongle) - Logitech MX Master 3s (Bluetooth and dongle)
I've changed the status back to "REPORTED", please let me know if you need more information.
Another thing we can check: Please run virt-viewer with WAYLAND_DEBUG=1, do a few scroll steps, and attach the output of that here
Created attachment 181764 [details] virt-viewer with WAYLAND_DEBUG=1 I have started virt-manager with the `WAYLAND_DEBUG=1` variable, and scrolled a couple of times down and up.
The scroll wheel behaviour was acting different than usual when I was capturing the logs. I used Google Chrome, instead of Firefox and it seems that using ozone-platform X11 (default) not only has the double scroll input bug, but also makes it skip scrolling. Launching Chrome with `--ozone-platform=wayland` fixes the skipped scrolls, but it still leaves me with the double scroll input bug. To reproduce the first skipped scrolling bug (affecting only the VM): 1. Start Google Chrome/Chromium with `--ozone-platform=X11`. 2. Go to a web page (https://fedoramagazine.org). 3. Start scrolling down, line by line slowly. To reproduce the second skipped scrolling bug (affecting both host and VM): 1. Start Google Chrome/Chromium with `--ozone-platform=X11`. 2. Have something else open that you can ALT+TAB to (Firefox, for example). 3. Go to a web page (https://fedoramagazine.org). 4. Scroll to the middle (so that we have enough space to go up/down). 5. Scroll down, once. 6. Press ALT+TAB, twice. (So Chrome loses and regains focus). 7. Scroll up, once. Repeating steps 5-7 will results in 0 scrolls. This can also be triggered simply by scrolling to the top of the page, scrolling down once and repeat.
The Wayland events KWin sends are definitely correct, with > axis_discrete(0, 1) or > axis_discrete(0, -1) each time. So this is a bug in the application(s) - please report it to the relevant apps.