# OnToolGUI(EditorWindow)

> This method is used to implement the custom terrain editor paint tool.

## Definition

* **Type:** Method
* **Namespace:** [UnityEditor.TerrainTools](/engine/6000.7/script-reference/unityeditor/terraintools.md)
* **Assembly:** UnityEditor

```csharp
public override void OnToolGUI(EditorWindow window)
```

### Parameters

**** (\[EditorWindow]\(/engine/6000.7/script-reference/unityeditor/editorwindow)): The window that is displaying the custom editor tool.