Reorderable lists now have a new field "EqualizeSizesOnDrag", default to false. When it is true it sets every item size (when being dragged over the current list) to the current size of the first element of the list.

true was the default behaviour before, and it might be useful in some cases so I left the option there, but in most use cases I encountered so far, and according to Issue 268 (https://bitbucket.org/UnityUIExtensions/unity-ui-extensions/issues/268/re-orderable-lists-different-width-height) the false behaviour is expected.

Scripts/Controls/ReorderableList/ReorderableList.cs

@@ -28,6 +28,10 @@ namespace UnityEngine.UI.Extensions
         [Tooltip("Should dropped items displace a current item if the list is full?\n " +
             "Depending on the dropped items origin list, the displaced item may be added, dropped in space or deleted.")]
         public bool IsDisplacable = false;
+        
+        // This sets every item size (when being dragged over this list) to the current size of the first element of this list
+        [Tooltip("Should items being dragged over this list have their sizes equalized?")]
+        public bool EqualizeSizesOnDrag = false; 
 
         public int maxItems = int.MaxValue;
 

Scripts/Controls/ReorderableList/ReorderableListElement.cs

@@ -505,7 +505,10 @@ namespace UnityEngine.UI.Extensions
         {
             Vector2 size = _draggingObjectOriginalSize;
 
-            if (_currentReorderableListRaycasted != null && _currentReorderableListRaycasted.IsDropable && _currentReorderableListRaycasted.Content.childCount > 0)
+            if (_currentReorderableListRaycasted != null
+                && _currentReorderableListRaycasted.IsDropable
+                && _currentReorderableListRaycasted.Content.childCount > 0
+                && _currentReorderableListRaycasted.EqualizeSizesOnDrag)
             {
                 var firstChild = _currentReorderableListRaycasted.Content.GetChild(0);
                 if (firstChild != null)