[BUG] MDANSE doesn't run on a Wayland desktop

[jamescrake-merani]

Background information
Your OS: Ubuntu 24.04
Python version: (e.g. 3.10, 3.11, ...)
MDANSE version: 2.0.1.post39+git.3cb88864.dirty
MDANSE_GUI version: 2.0.1.post39+git.3cb88864.dirty
CPU architecture: x86_64

What were you doing?
Trying to run MDANSE through uv run mdanse_gui

What went wrong?
I get the following error:

2026-09-02 17:13:30,644 - INFO - process[116224] - Resources 56 - Resources are in /home/dlp54594/python/MDANSE/MDANSE_GUI/Src/MDANSE_GUI/Icons
X Error of failed request:  BadWindow (invalid Window parameter)
  Major opcode of failed request:  12 (X_ConfigureWindow)
  Resource id in failed request:  0x18941400
  Serial number of failed request:  7
  Current serial number in output stream:  8

Suggested fix (optional)
This problem is a bit odd, as it shouldn't be trying to configure an X11 window considering I'm on wayland. I don't get this problem when running mdanse_units_editor, so I suspect this may have something to do with how MDANSE is launched.

Additional details (optional)
Add any other information that seems relevant to this problem.

[MBartkowiakSTFC]

Possibly related to #414

[jamescrake-merani]

Yes I just tried to the fix in that issue, and it worked. Its a bit odd that its only happening to mdanse_gui though, as others in the same project seem to work fine.

I can have a play around when I've got some time if you'd like.

[MBartkowiakSTFC]

@jamescrake-merani Thanks, we'll definitely ask you to do some testing so we can have a permanent fix for this.

So, do the mdanse_periodic_table and mdanse_units_editor work for you without any problems? This may be related to the VTK 3D view being present in the main GUI, but not in the smaller dialogs.

[jamescrake-merani]

Yep, I'm able to launch both of those without any issues, and they seem to work fine.

I didn't think about VTK but if it has its own logic for drawing stuff to the screen which bypasses QT then that could be the problem.

[MBartkowiakSTFC]

It seems that two weeks ago VTK 9.7 came out. For the first time it is supposed to have support for Wayland:
https://docs.vtk.org/en/latest/release_details/9.7/hardware-windows-and-wayland.html

I don't know yet what changes we would have to make in MDANSE to make sure that we are using the vtkWaylandRenderWindowInteractor when Wayland is running. On our side everything is handled by QVTKRenderWindowInteractor.

This might not be important here, since you did get MDANSE_GUI to work, but just for general background: it seems that other projects using VTK such as ParaView have relied on the users installing XWayland https://discourse.paraview.org/t/how-does-paraview-work-with-wayland-and-how-will-it-work-in-the-future/16770

@jamescrake-merani What is your VTK version, and does your system have xwayland installed?

[jamescrake-merani]

uv pip freeze says I'm on vtk 9.7.0

My system definitely has xwayland installed because I can run other applications that only support X11. In fact, it looks like QT_QPA_PLATFORM=xcb is forcing MDANSE to run under xwayland, which is probably why VTK doesn't crash when that environment variable is used.

My suspicion is that by default, QT wants to run under Wayland so it does so, but VTK still assumes its running under X11 so it tries to draw to the XWindow, and then crashes because its not in an X11 session.

[MBartkowiakSTFC]

It seems that the PyVista developers were working on a way to make VTK run correctly with Qt and Wayland, with some success. This PR seems to be the most informative one: pyvista/pyvistaqt#848