# CreateChildListForCollapsedParent()

> Creates a dummy TreeViewItem list. Useful when overriding TreeView<TIdentifier>.BuildRows to prevent building a full tree of items.

## Definition

* **Type:** Method
* **Namespace:** [UnityEditor.IMGUI.Controls](/engine/6000.6/script-reference/unityeditor/imgui/controls.md)
* **Assembly:** UnityEditor.CoreModule

```csharp
protected static List<TreeViewItem<TIdentifier>> CreateChildListForCollapsedParent()
```

### Returns

| Type                                                                                                | Description |
| --------------------------------------------------------------------------------------------------- | ----------- |
| [List\<TreeViewItem\<T>>](https://learn.microsoft.com/dotnet/api/system.collections.generic.list-1) |             |

### Remarks

When building the rows in BuildRows, it is not necessary to create items for descendants of collapsed items because these descendants are not visible. This can be a useful optimization, particularly in large trees or trees that change often. However, collapsed items still require a foldout arrow to be shown to indicate the presence of children. This is achieved by creating a dummy list and assigning it to the [TreeViewItem.children](/engine/6000.6/script-reference/unityeditor/imgui/controls/treeviewitem/children.md) property of the collapsed parent TreeViewItem.

Additional Resources: [TreeView\<TIdentifier>.BuildRows](/engine/6000.6/script-reference/unityeditor/imgui/controls/treeview1/buildrows.md). [TreeView\<TIdentifier>.IsChildListForACollapsedParent](/engine/6000.6/script-reference/unityeditor/imgui/controls/treeview1/ischildlistforacollapsedparent.md).