Hello,

If you encounter a rendering problem with python panels, it is likely due to an issue with Qt's WebEngine running on a system with a newer glibc version (i.e. Ubuntu 22.04 LTS). Basically, any panels that display Qt web content, such as the Python Panel Calendar example and the Python Panel error viewer, will not function out-of-the-box.

The workaround is to turn off sandboxing in Qt WebEngine's Chromium code by setting QTWEBENGINE_CHROMIUM_FLAGS='--no-sandbox' in the environment before launching Houdini. The reason why we do not set this environment variable automatically on Houdini startup is because there are inherent security risks with turning off sandboxing in Chromium:
https://chromium.googlesource.com/chromium/src/+/HEAD/docs/mac/sandbox_debugging.md [chromium.googlesource.com]

So turn off sandboxing at your own risk though we haven't encountered any issues thus far in-house when turning off sandboxing.

Note that newer Chromium versions, such as the one that ships in Qt 6, does not experience this problem. When we release Houdini with Qt 6 support, the problem will go away.

Also note that it is not feasible for us to backport a fix to Houdini's Qt 5 build.