save preferences when clicking OK (fixes #608)

app/src/processing/app/Preferences.java

@@ -220,8 +220,8 @@ public class Preferences {
 
 
   static public void save() {
-    // On startup it'll be null, don't worry about it. It's trying to update
-    // the prefs for the open sketch before Preferences.init() has been called.
+    // On startup, this is null, but ignore it. It's trying to update the
+    // prefs for the open sketch before Preferences.init() has been called.
     if (preferencesFile != null) {
       try {
         File dir = preferencesFile.getParentFile();

app/src/processing/app/ui/PreferencesFrame.java

@@ -830,6 +830,9 @@ public class PreferencesFrame {
     for (Editor editor : base.getEditors()) {
       editor.applyPreferences();
     }
+
+    // https://github.com/processing/processing4/issues/608
+    Preferences.save();
   }
 
 

todo.txt

@@ -1,5 +1,6 @@
 1291 (4.1.3 or 4.2)
-
+X preferences.txt is not saved when closing Processing under certain circumstances
+X   https://github.com/processing/processing4/issues/608
 
 manager
 X add 'exports' to the library parameters