For anybody who wants to help test this –
- Download this file: https://github.com/tabreturn/processing.py-for-processing-4/raw/main/PythonMode-4.0a4.zip
- Extract it and place the PythonMode directory in your sketchbook modes directory (see File > Preferences menu in Processing for this location). Replace any existing PythonMode files.
If you’re running Processing 3 and 4 on the same system, they both use the same sketchbook location (but this build seems to work fine in both).
To report issues or find out more:
https://github.com/jdf/processing.py/issues/382#issuecomment-862953883