It do appear to be a regression. It works fine on Fedora 38 and previous versions of Fedora. On my machine and other machines. After upgrading to Fedora 39, when running gnome-shell under Wayland (default), the content of the TigerVNC viewer window is flickering, and redraw rectangles are easily visible. It draws a lot of regions as white, and flickers, even if there are no changes being redrawn on the server side. Entering full screen mode (context menu -> Full screen), usually causes flicker to subside, and the viewer can be used. But it is unusable when running windowed. I also tried recompiling tigervnc from source, and the problem persists. It might be issue in the compositor or Xwayland (tigervnc is using X11) Reproducible: Always Steps to Reproduce: 1.Start vncviewer and connect to a server Actual Results: Happens every time. Massive flicker of white areas, slow readraw. tigervnc-1.13.1-4.fc39.x86_64 tigervnc-license-1.13.1-4.fc39.noarch tigervnc-server-minimal-1.13.1-4.fc39.x86_64 tigervnc-icons-1.13.1-4.fc39.noarch Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz Linux 6.5.0-0.rc7.20230821gitf7757129e3de.50.fc39.x86_64 mutter-common-45~rc-2.fc39.noarch mutter-45~rc-2.fc39.x86_64 Vendor: Intel (0x8086) Device: Mesa Intel(R) Iris(R) Plus Graphics 655 (CFL GT3) (0x3ea5) Version: 23.2.0 Accelerated: yes Video memory: 15591MB OpenGL renderer string: Mesa Intel(R) Iris(R) Plus Graphics 655 (CFL GT3) OpenGL core profile version string: 4.6 (Core Profile) Mesa 23.2.0-rc3
tigervnc-1.13.1-4.fc39.x86_64 tigervnc-license-1.13.1-4.fc39.noarch tigervnc-server-minimal-1.13.1-4.fc39.x86_64 tigervnc-icons-1.13.1-4.fc39.noarch
If it was unclear. When running Gnome classic, under X11, the problem does not happen. And tigervnc works perfectly.
There is probably nothing we can do about that in Tigervnc. There is going to be a native Wayland support in Fltk, which is the toolkit Tigervnc uses for vncviewer and I expect it will fix your issues.
I do not think it is a problem in Tigervnc, nor that it requires a fix in tigervnc. It is just a trigger. I think the issue is in Xwayland. I just manually updated from xorg-x11-server-Xwayland-23.2.0-1.fc39.x86_64 to xorg-x11-server-Xwayland-23.2.1-1.fc39.x86_64.rpm (downloaded from koji), killed Xwayland, and relaunched vncviewer and it appears the regression is gone. Please reassign to Xwayland.
It appears that new Xwayland was released just hours ago. https://bugzilla.redhat.com/show_bug.cgi?id=2239813 https://koji.fedoraproject.org/koji/buildinfo?buildID=2292845 There are 2 fix commits, and one of the commits in fact references a vnc issue: https://gitlab.freedesktop.org/xorg/xserver/-/commits/xwayland-23.2/ https://gitlab.freedesktop.org/xorg/xserver/-/commit/ad46baaa564166569577aa78488ac50544a59072 https://gitlab.freedesktop.org/xorg/xserver/-/issues/1575 Original ArchLinux bug report: https://bbs.archlinux.org/viewtopic.php?id=288243
As Witold already pointed out, this is https://gitlab.freedesktop.org/xorg/xserver/-/issues/1575 fixed with Xwayland 23.2.1 whose release is pending in F39, see https://bodhi.fedoraproject.org/updates/FEDORA-2023-64508ee019