If GTK libraries have different versions an attempt to load them in the same process will cause fatal error.

After the JDK-8145547 JDK may work with 2 versions of GTK: 2 and 3 and has a built-in mechanism to detect the library version it should use to avoid loading of incompatible library version. This mechanism tries to detect if the certain version of GTK is pre-loaded in the process. But it fails to detect this in case of SWT embedding.

Test AWT_SWT/Manual/SwingComp/SwingAppTest.java crashes with GTK LnF, unless the GTK version is set manually to 3: -Djdk.gtk.version=3.