--- mockup/node_modules/select2/select2.js-orig	2020-10-09 21:12:08.763799718 +0200
+++ mockup/node_modules/select2/select2.js-new	2020-10-09 21:11:42.607521087 +0200
@@ -1,6 +1,10 @@
 /*
 Copyright 2012 Igor Vaynberg
 
+CUTOMIZED version for Plone RelatedItems pattern!
+See this for changes made, based on version 3.5.x branch of select2:
+https://github.com/collective/select2-3.5.3-custom
+
 Version: 3.5.4 Timestamp: Sun Aug 30 13:30:32 EDT 2015
 
 This software is licensed under the Apache License, Version 2.0 (the "Apache License") or the GNU
@@ -1728,7 +1732,7 @@
 
         // abstract
         findHighlightableChoices: function() {
-            return this.results.find(".select2-result-selectable:not(.select2-disabled):not(.select2-selected)");
+            return this.results.find(".select2-result-selectable:not(.select2-disabled)");
         },
 
         // abstract
@@ -1739,7 +1743,7 @@
             while (index > -1 && index < choices.length) {
                 index += delta;
                 var choice = $(choices[index]);
-                if (choice.hasClass("select2-result-selectable") && !choice.hasClass("select2-disabled") && !choice.hasClass("select2-selected")) {
+                if (choice.hasClass("select2-result-selectable") && !choice.hasClass("select2-disabled")) {
                     this.highlight(index);
                     break;
                 }
@@ -2041,7 +2045,7 @@
               return;
             }
             var index=this.highlight(),
-                highlighted=this.results.find(".select2-highlighted"),
+                highlighted=this.results.find(".select2-highlighted:not(.select2-selected)"),
                 data = highlighted.closest('.select2-result').data("select2-data");
 
             if (data) {
@@ -2949,7 +2953,7 @@
                     }
                     return;
                 } else if (((e.which === KEY.BACKSPACE && this.keydowns == 1)
-                    || e.which == KEY.LEFT) && (pos.offset == 0 && !pos.length)) {
+                    || e.which == KEY.LEFT && !this.opened()) && (pos.offset == 0 && !pos.length)) {
 
                     this.selectChoice(selection.find(".select2-search-choice:not(.select2-locked)").last());
                     killEvent(e);