Add ShowInPlayMode to HideInEditor attribute for properties/fields that should display in editor only during play mode

Source/Editor/CustomEditors/Editors/GenericEditor.cs

@@ -261,6 +261,7 @@ namespace FlaxEditor.CustomEditors.Editors
         public static List<ItemInfo> GetItemsForType(ScriptType type, bool useProperties, bool useFields, bool usePropertiesWithoutSetter = false)
         {
             var items = new List<ItemInfo>();
+            var isPlayMode = Editor.IsPlayMode;
 
             if (useProperties)
             {
@@ -278,7 +279,7 @@ namespace FlaxEditor.CustomEditors.Editors
                         continue;
 
                     // Skip hidden fields, handle special attributes
-                    if ((!p.IsPublic && !showInEditor) || attributes.Any(x => x is HideInEditorAttribute))
+                    if ((!p.IsPublic && !showInEditor) || attributes.Any(x => x is HideInEditorAttribute hide && (!isPlayMode || !hide.ShowInPlayMode)))
                         continue;
 
                     items.Add(new ItemInfo(p, attributes));
@@ -293,11 +294,10 @@ namespace FlaxEditor.CustomEditors.Editors
                 for (int i = 0; i < fields.Length; i++)
                 {
                     var f = fields[i];
-
                     var attributes = f.GetAttributes(true);
 
                     // Skip hidden fields, handle special attributes
-                    if ((!f.IsPublic && !attributes.Any(x => x is ShowInEditorAttribute)) || attributes.Any(x => x is HideInEditorAttribute))
+                    if ((!f.IsPublic && !attributes.Any(x => x is ShowInEditorAttribute)) || attributes.Any(x => x is HideInEditorAttribute hide && (!isPlayMode || !hide.ShowInPlayMode)))
                         continue;
 
                     items.Add(new ItemInfo(f, attributes));

Source/Engine/Scripting/Attributes/Editor/HideInEditorAttribute.cs

@@ -10,6 +10,11 @@ namespace FlaxEngine
     [Serializable]
     public sealed class HideInEditorAttribute : Attribute
     {
+        /// <summary>
+        /// Shows the variable only in play mode (when the game is running), otherwise it will be hidden. Useful for runtime fields or properties to remain invisible at edit time.
+        /// </summary>
+        public bool ShowInPlayMode;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="HideInEditorAttribute"/> class.
         /// </summary>