UNIHIKER and OpenCV

Hello!

The basic Hello OpenCV exercise fails with the following message:

qt.qpa.xcb: could not connect to display 
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/usr/local/lib/python3.7/dist-packages/cv2/qt/plugins" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: xcb.

Aborted
 

The Python (3.7.1) script reads the image file correctly but cannot display it with the imshow function. The xcb library is installed as reported by apt:

libxcb1 is already the newest version (1.13.1-2).

libxcb1 set to manually installed.

The OpenCV version is 4.7.0

Is there any workaround for the anomaly? Thanks.

Regards.