# activeToolChanging

> Defines an event handler for when the active tool changes.

## Definition

* **Type:** Event
* **Namespace:** [UnityEditor.EditorTools](/engine/6000.5/script-reference/unityeditor/editortools.md)
* **Assembly:** UnityEditor.CoreModule

```csharp
public static event Action activeToolChanging
```

### Remarks

Use this event along with [ToolManager.IsActiveTool](/engine/6000.5/script-reference/unityeditor/editortools/toolmanager/isactivetool.md) to be notified when an [EditorTool](/engine/6000.5/script-reference/unityeditor/editortools/editortool.md) is deactivated.