prefer "Isabelle DejaVu Sans", even for headless batch-build (session_graph.pdf);
--- a/src/Pure/Tools/build.scala Wed Nov 28 16:27:21 2018 +0100
+++ b/src/Pure/Tools/build.scala Wed Nov 28 16:33:45 2018 +0100
@@ -418,6 +418,8 @@
val store = Sessions.store(build_options, system_mode)
+ Isabelle_Fonts.init()
+
/* session selection and dependencies */
--- a/src/Tools/Graphview/etc/options Wed Nov 28 16:27:21 2018 +0100
+++ b/src/Tools/Graphview/etc/options Wed Nov 28 16:33:45 2018 +0100
@@ -2,7 +2,7 @@
section "Graphview"
-option graphview_font_family : string = "Helvetica"
+option graphview_font_family : string = "Isabelle DejaVu Sans"
-- "base font family (notably for PDF)"
option graphview_font_size : int = 12