more robust GUI setup via Java, instead of shell script;
support for automatic / approximative GDK_SCALE for Linux;

--- a/Admin/components/components.sha1	Thu Jun 12 16:54:28 2025 +0200
+++ b/Admin/components/components.sha1	Fri Jun 13 15:18:16 2025 +0200
@@ -196,6 +196,7 @@
 f582c621471583d06e00007c6acc01376c7395af isabelle_setup-20230206.tar.gz
 d30109fe63cec35c31cee9ffd17ae3a13c1e6a33 isabelle_setup-20230922.tar.gz
 cd92c141883f0f6a18adceb885316c8b6119e648 isabelle_setup-20240327.tar.gz
+ed96100db1c7fd0beee0c93929609cab42e952b8 isabelle_setup-20250613.tar.gz
 f23037b322b968c61350f9ec9995a4f397e6c71c javamail-1.4.7.tar.gz
 18e6b60ceb98e327fbf14e52f4613dd5b0483d2f javamail-20240109.tar.gz
 dc826bc0d715cd4190d1bb2e7122321eea5355de javamail-20250122.tar.gz

--- a/Admin/components/main	Thu Jun 12 16:54:28 2025 +0200
+++ b/Admin/components/main	Fri Jun 13 15:18:16 2025 +0200
@@ -12,7 +12,7 @@
 flatlaf-3.6-2
 foiltex-2.1.4b
 isabelle_fonts-20241227
-isabelle_setup-20240327
+isabelle_setup-20250613
 javamail-20250122
 jdk-21.0.6
 jedit-20250521

--- a/NEWS	Thu Jun 12 16:54:28 2025 +0200
+++ b/NEWS	Fri Jun 13 15:18:16 2025 +0200
@@ -44,6 +44,12 @@
 Dark" imitate original macOS more closely. This is the default for the
 bundled application on macOS.
 
+* Automatic GUI scaling on Linux, based on global GDK_SCALE for Java.
+This is only an approximation: an integer factor that applies uniformly
+to all displays. In contrast, Windows and macOS work with accurate GUI
+scaling for each individual display, based on operating system settings
+and FlatLaf defaults.
+
 * GUI rendering of the gutter is now more accurate, using scaled icons
 to fit precisely into the available space.
 

--- a/lib/scripts/java-gui-setup	Thu Jun 12 16:54:28 2025 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,12 +0,0 @@
-#!/usr/bin/env bash
-#
-# java-gui-setup --- platform-specific setup for Java/Swing GUI applications
-
-case "$ISABELLE_PLATFORM_FAMILY" in
-  macos*)
-    JAVA_VERSION="$("$ISABELLE_JDK_HOME/bin/java" -version 2>&1 | head -n 1 | cut -d '"' -f2)"
-    JAVA_DOMAIN="com.azul.zulu.${JAVA_VERSION}.java"
-    defaults read "$JAVA_DOMAIN" AppleWindowTabbingMode >/dev/null 2>/dev/null ||
-      defaults write "$JAVA_DOMAIN" AppleWindowTabbingMode manual >/dev/null 2>/dev/null
-    ;;
-esac

--- a/src/Pure/Admin/build_release.scala	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Pure/Admin/build_release.scala	Fri Jun 13 15:18:16 2025 +0200
@@ -306,7 +306,7 @@
 
 declare -a JAVA_OPTIONS=($(grep -v '^#' "$ISABELLE_HOME/Isabelle.options"))
 
-"$ISABELLE_HOME/bin/isabelle" env "$ISABELLE_HOME/lib/scripts/java-gui-setup"
+eval $(isabelle java isabelle.setup.Setup gui_setup)
 
 exec "$ISABELLE_JDK_HOME/bin/java" \
   "-Disabelle.root=$ISABELLE_HOME" "${JAVA_OPTIONS[@]}" \
@@ -665,19 +665,6 @@
 
         platform match {
           case Platform.Family.linux_arm | Platform.Family.linux =>
-            File.change(isabelle_target + jedit_options) {
-              _.replaceAll("jedit_reset_font_size : int =.*", "jedit_reset_font_size : int = 24")
-            }
-
-            File.change(isabelle_target + jedit_props) {
-              _.replaceAll("console.fontsize=.*", "console.fontsize=18")
-               .replaceAll("helpviewer.fontsize=.*", "helpviewer.fontsize=18")
-               .replaceAll("metal.primary.fontsize=.*", "metal.primary.fontsize=18")
-               .replaceAll("metal.secondary.fontsize=.*", "metal.secondary.fontsize=18")
-               .replaceAll("view.fontsize=.*", "view.fontsize=24")
-               .replaceAll("view.gutter.fontsize=.*", "view.gutter.fontsize=16")
-            }
-
             make_isabelle_options(
               isabelle_target + Path.explode("Isabelle.options"), java_options)
 

--- a/src/Pure/System/platform.scala	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Pure/System/platform.scala	Fri Jun 13 15:18:16 2025 +0200
@@ -11,8 +11,8 @@
   /* platform family */
 
   val is_windows: Boolean = isabelle.setup.Environment.is_windows()
-  val is_linux: Boolean = System.getProperty("os.name", "") == "Linux"
-  val is_macos: Boolean = System.getProperty("os.name", "") == "Mac OS X"
+  val is_linux: Boolean = isabelle.setup.Environment.is_linux()
+  val is_macos: Boolean = isabelle.setup.Environment.is_macos()
   val is_unix: Boolean = is_linux || is_macos
 
   def is_arm: Boolean = cpu_arch.startsWith("arm")

--- a/src/Tools/Setup/etc/build.props	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Tools/Setup/etc/build.props	Fri Jun 13 15:18:16 2025 +0200
@@ -4,5 +4,6 @@
   src/Build.java \
   src/Environment.java \
   src/Exn.java \
+  src/GUI_Setup.java \
   src/Library.java \
   src/Setup.java

--- a/src/Tools/Setup/src/Environment.java	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Tools/Setup/src/Environment.java	Fri Jun 13 15:18:16 2025 +0200
@@ -30,6 +30,8 @@
     {
         return System.getProperty("os.name", "").startsWith("Windows");
     }
+    public static Boolean is_linux() { return System.getProperty("os.name", "").equals("Linux"); }
+    public static Boolean is_macos() { return System.getProperty("os.name", "").equals("Mac OS X"); }
 
 
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Tools/Setup/src/GUI_Setup.java	Fri Jun 13 15:18:16 2025 +0200
@@ -0,0 +1,43 @@
+/*  Title:      Tools/Setup/src/GUI_Setup.scala
+    Author:     Makarius
+
+Platform-specific setup for Java/Swing GUI applications.
+*/
+
+package isabelle.setup;
+
+import java.util.List;
+
+import com.formdev.flatlaf.FlatLightLaf;
+import com.formdev.flatlaf.util.UIScale;
+
+
+public class GUI_Setup
+{
+    public static String gui_setup()
+    {
+        String msg = "";
+
+        if (Environment.is_linux()) {
+            if (FlatLightLaf.setup()) {
+                int scale = (int) UIScale.getUserScaleFactor();
+                if (scale > 1) { msg = "export GDK_SCALE=" + scale; }
+            }
+        }
+        else if (Environment.is_macos()) {
+            String java_domain = "com.azul.zulu." + System.getProperty("java.version") + ".java";
+            if (!apple_tabbing_mode("read", java_domain)) {
+                apple_tabbing_mode("write", java_domain);
+            }
+        }
+
+        return msg;
+    }
+
+    public static boolean apple_tabbing_mode(String op, String domain)
+    {
+        List<String> cmd = java.util.List.of("defaults", op, domain, "AppleWindowTabbingMode");
+        try { return Environment.exec_process(cmd, null, null, false).ok(); }
+        catch (Exception e) { return false; }
+    }
+}

--- a/src/Tools/Setup/src/Setup.java	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Tools/Setup/src/Setup.java	Fri Jun 13 15:18:16 2025 +0200
@@ -48,6 +48,11 @@
                     check_args(n == 1);
                     echo(Environment.join_standard_paths(Build.classpath()));
                     break;
+                case "gui_setup":
+                    check_args(n == 1);
+                    String msg = GUI_Setup.gui_setup();
+                    if (msg != null && !msg.isEmpty()) { echo(msg); }
+                    break;
                 case "services":
                     check_args(n == 1);
                     for (String s : Build.services()) { echo(s); }

--- a/src/Tools/jEdit/lib/Tools/jedit	Thu Jun 12 16:54:28 2025 +0200
+++ b/src/Tools/jEdit/lib/Tools/jedit	Fri Jun 13 15:18:16 2025 +0200
@@ -168,7 +168,7 @@
 
 if [ "$BUILD_ONLY" = false ]
 then
-  "$ISABELLE_HOME/lib/scripts/java-gui-setup"
+  eval $(isabelle java isabelle.setup.Setup gui_setup)
 
   export JEDIT_SESSION_DIRS JEDIT_LOGIC JEDIT_LOGIC_ANCESTOR JEDIT_LOGIC_REQUIREMENTS \
     JEDIT_INCLUDE_SESSIONS JEDIT_PRINT_MODE JEDIT_NO_BUILD JEDIT_ISABELLE_OPTIONS JEDIT_BUILD_MODE