From 1fb6586dff6c37a245f40865adbc0f214a7121ca Mon Sep 17 00:00:00 2001
From: Chandler Cox <mr.chandlercox@gmail.com>
Date: Sat, 19 Jul 2025 16:09:33 -0500
Subject: [PATCH 1/2] Add collection item duplication.

---
 .../CustomEditors/Editors/CollectionEditor.cs | 27 +++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/Source/Editor/CustomEditors/Editors/CollectionEditor.cs b/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
index cfc11d5a5..50b3e47d5 100644
--- a/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
+++ b/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
@@ -70,7 +70,9 @@ namespace FlaxEditor.CustomEditors.Editors
                 menu.ItemsContainer.RemoveChildren();
 
                 menu.AddButton("Copy", linkedEditor.Copy);
-                var b = menu.AddButton("Paste", linkedEditor.Paste);
+                var b = menu.AddButton("Duplicate", () => Editor.Duplicate(Index));
+                b.Enabled = linkedEditor.CanPaste && !Editor._readOnly;
+                b = menu.AddButton("Paste", linkedEditor.Paste);
                 b.Enabled = linkedEditor.CanPaste && !Editor._readOnly;
 
                 menu.AddSeparator();
@@ -404,8 +406,10 @@ namespace FlaxEditor.CustomEditors.Editors
                 var menu = new ContextMenu();
 
                 menu.AddButton("Copy", linkedEditor.Copy);
+                var b = menu.AddButton("Duplicate", () => Editor.Duplicate(Index));
+                b.Enabled = linkedEditor.CanPaste && !Editor._readOnly;
                 var paste = menu.AddButton("Paste", linkedEditor.Paste);
-                paste.Enabled = linkedEditor.CanPaste;
+                paste.Enabled = linkedEditor.CanPaste && !Editor._readOnly;
 
                 if (_canReorder)
                 {
@@ -741,6 +745,25 @@ namespace FlaxEditor.CustomEditors.Editors
             cloned[srcIndex] = tmp;
             SetValue(cloned);
         }
+        
+        /// <summary>
+        /// Duplicates the list item.
+        /// </summary>
+        /// <param name="index">The index to duplicate.</param>
+        public void Duplicate(int index)
+        {
+            if (IsSetBlocked)
+                return;
+
+            var count = Count;
+            Resize(count + 1);
+            RefreshInternal(); // Force update values.
+            Shift(count, index + 1);
+            RefreshInternal(); // Force update values.
+            var cloned = CloneValues();
+            cloned[index + 1] = Utilities.Utils.CloneValue(cloned[index]);
+            SetValue(cloned);
+        }
 
         /// <summary>
         /// Shifts the specified item at the given index and moves it through the list to the other item. It supports undo.

From 824b49dd883443c7a20384de4aa83bedb43f3483 Mon Sep 17 00:00:00 2001
From: Chandler Cox <mr.chandlercox@gmail.com>
Date: Tue, 26 Aug 2025 20:25:02 -0500
Subject: [PATCH 2/2] Better duplication of collection.

---
 .../CustomEditors/Editors/CollectionEditor.cs | 23 +++++++++++++------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/Source/Editor/CustomEditors/Editors/CollectionEditor.cs b/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
index 50b3e47d5..a0ee8d3dc 100644
--- a/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
+++ b/Source/Editor/CustomEditors/Editors/CollectionEditor.cs
@@ -756,13 +756,22 @@ namespace FlaxEditor.CustomEditors.Editors
                 return;
 
             var count = Count;
-            Resize(count + 1);
-            RefreshInternal(); // Force update values.
-            Shift(count, index + 1);
-            RefreshInternal(); // Force update values.
-            var cloned = CloneValues();
-            cloned[index + 1] = Utilities.Utils.CloneValue(cloned[index]);
-            SetValue(cloned);
+            var newValues = Allocate(count + 1);
+            var oldValues = (IList)Values[0];
+   
+            for (int i = 0; i <= index; i++)
+            {
+                newValues[i] = oldValues[i];
+            }
+
+            newValues[index + 1] = Utilities.Utils.CloneValue(oldValues[index]);
+
+            for (int i = index + 1; i < count; i++)
+            {
+                newValues[i + 1] = oldValues[i];
+            }
+
+            SetValue(newValues);
         }
 
         /// <summary>