Having managed to get ProjectLibre to open without crashing:
… I face another difficulty - freezing - which can be brought on by trying to save the project document, close the open document, close the ProjectLibre window etc.
This seems to be a ProjectLibre problem and a bug report is open:
My work-around is to install MX Linux in a VM and use ProjectLibre in that where it works as expected.
Does anyone have a different experience with ProjectLibre on 18.04 e.g other work-arounds or does it “just work” for you?
A simple work-around has now been posted on Sourceforge, which I have added to my post about generalised Java-related problems on 18.04:
I hope that helps users of ProjectLibre on Ubuntu-Mate.