--- a/etc/settings Sat Oct 06 15:06:10 2018 +0200
+++ b/etc/settings Sat Oct 06 17:37:09 2018 +0200
@@ -14,7 +14,7 @@
ISABELLE_SCALAC_OPTIONS="-encoding UTF-8 -nowarn -target:jvm-1.8 -Xmax-classfile-name 130 -J-Xms128m -J-Xmx1024m -J-Xss2m"
-ISABELLE_JAVA_SYSTEM_OPTIONS="-server -Dfile.encoding=UTF-8 -Disabelle.threads=0"
+ISABELLE_JAVA_SYSTEM_OPTIONS="-server -Dfile.encoding=UTF-8 -Disabelle.threads=0 -Djdk.gtk.version=2.2"
ISABELLE_TOOL_JAVA_OPTIONS="-Djava.awt.headless=true -Xms512m -Xmx2560m -Xss16m"