src/Tools/jEdit/src/jedit_options.scala

         if (stored != b) {
           PIDE.options.bool(name) = b
           PIDE.session.update_options(PIDE.options.value)
         }
       }
-    def load() { selected = stored }
+    def load(): Unit = { selected = stored }
     load()
   }
 }
 
 class JEdit_Options(init_options: Options) extends Options_Variable(init_options)