I just updated the SourceCity configurationOf, using the latest version of NBOpenGL. It's running on Linux but i have many artifacts, i just report you that bug :)
I also have 3 new empty window opened. And if i close them, image closing and i have this error message in shell.
wawan@wawan-MS-16F1:~/Downloads/latest$ pharo Pharo-30252.image�
XIO: �fatal IO error 4 (Interrupted system call) on X server ":0"
� � � after 48 requests (48 known processed) with 1 events remaining.