# TreeView.DoFoldoutCallback

> Callback signature used to override the TreeView foldout. See TreeView.foldoutOverride.

## Definition

* **Type:** Delegate
* **Namespace:** [UnityEditor.IMGUI.Controls](/engine/6000.0/script-reference/unityeditor/imgui/controls.md)
* **Assembly:** UnityEditor

```csharp
public delegate bool TreeView.DoFoldoutCallback(Rect position, bool expandedState, GUIStyle style)
```