Add alternate array index style, with setting

src/Editor/Editor.php

@@ -806,7 +806,7 @@ class Editor
                 'quotedKeys' => (Settings::$editorQuotedKeys?$mark:$clear)."Quoted keys",
                 'tailLine' => (Settings::$tailLine?$mark:$clear)."Show tail line",
                 'indentationGuides' => (Settings::$indentationGuides?$mark:$clear)."Show indentation guides",
-                //'done' => "  Done"
+                'highlightIndices' => (Settings::$highlightIndices?$mark:$clear)."Highlight array indices",
             ];
             $sel = (new Menu($this->term, $items, "Settings"))
                 ->display(0, 0, 40, 0, $sel);
@@ -827,6 +827,9 @@ class Editor
                 case 'indentationGuides':
                     Settings::$indentationGuides = !Settings::$indentationGuides;
                     break;
+                case 'highlightIndices':
+                    Settings::$highlightIndices = !Settings::$highlightIndices;
+                    break;
             }
         } while ($sel);
         $this->redrawEditor();

src/List/TreeList.php

@@ -195,7 +195,11 @@ class TreeList implements Countable, IteratorAggregate
                 }." ";
             }
             echo (is_int($entry->key)
-                ?"\e[36;2m\u{e0b6}\e[7m#{$entry->key}\e[27m\u{e0b4}\e[22;37m "
+                
+                ?(Settings::$highlightIndices
+                    ?"\e[36;2m\u{e0b6}\e[7m#{$entry->key}\e[27m\u{e0b4}\e[22;37m "
+                    :"\e[36;2m#{$entry->key}\e[22;37m "
+                )
                 :(Settings::$editorQuotedKeys
                     ? "\e[36m\"{$entry->key}\":\e[37m "
                     : "\e[36m{$entry->key}:\e[37m "

src/Settings.php

@@ -16,6 +16,8 @@ class Settings
 
     public static bool $tailLine = true;
 
+    public static bool $highlightIndices = true;
+
     public static function load(string $filename): void
     {
         if (file_exists($filename) && is_readable($filename)) {
@@ -25,6 +27,7 @@ class Settings
             self::$indentationGuides = $data->indentationGuides ?? true;
             self::$collapseBefore = $data->collapseBefore ?? true;
             self::$tailLine = $data->tailLine ?? true;
+            self::$highlightIndices = $data->highlightIndices ?? true;
         }
     }
 
@@ -37,6 +40,7 @@ class Settings
             'collapseBefore' => self::$collapseBefore,
             'highlightRow' => self::$highlightRow,
             'tailLine' => self::$tailLine,
+            'highlightIndices' => self::$highlightIndices,
         ], JSON_UNESCAPED_SLASHES|JSON_PRETTY_PRINT)."\n";
         @file_put_contents($filename, $data);
     }