Posted by Wade Walker on Feb 03, 2019; 4:57pm
URL: https://forum.jogamp.org/NewtCanvasSWT-Linux-Exception-with-GTK-VERSION-tp4039442p4039462.html

I replicated the OP's bug, and started on the fix. It's a little more involved than just getting GTK_VERSION from org.eclipse.swt.internal.gtk.GTK instead of org.eclipse.swt.internal.gtk.OS. There are also several functions that migrated from org.eclipse.swt.internal.gtk.OS to a new class org.eclipse.swt.internal.gtk.GDK in newer versions of SWT, and the function gdk_window_set_back_pixmap() seems to have disappeared altogether in newer versions of GTK. Luckily, we're only ever setting the back pixmap to null, so we can replace that call with gdk_window_set_background_pattern() as they did in  https://git.eclipse.org/r/#/c/56351/3/bundles/org.eclipse.swt/Eclipse+SWT/gtk/org/eclipse/swt/widgets/Composite.java.