---
title: "FocusEventModifierNode"
description: "Implement this interface create a modifier node that can be used to observe focus state changes
to a [FocusTargetNode] down the hierarchy."
type: "interface"
---

<div class='type'>Interface</div>


<a id='references'></a>

<div class='sourceset sourceset-common'>Common</div>



```kotlin
interface FocusEventModifierNode : DelegatableNode
```


Implement this interface create a modifier node that can be used to observe focus state changes
to a `FocusTargetNode` down the hierarchy.


## Functions

```kotlin
fun onFocusEvent(focusState: FocusState)
```


A parent FocusEventNode is notified of `FocusState` changes to the `FocusTargetNode`
associated with this `FocusEventModifierNode`.