As a workaround, I keep openjdk-11* at the version 11.0.2+9-3ubuntu1~18.04.3 (locked the version). This way, Scilab from the repository is functional with GUI.
As a workaround, I keep openjdk-11* at the version 11.0.2+ 9-3ubuntu1~ 18.04.3 (locked the version). This way, Scilab from the repository is functional with GUI.