> ## Documentation Index
> Fetch the complete documentation index at: https://docs.omni.co/llms.txt
> Use this file to discover all available pages before exploring further.

# fullscreen:set embed event

> Sets the fullscreen presentation state of the embedded Omni session.

Use this event to programmatically control the fullscreen state of your embedded Omni session and build custom fullscreen controls in the parent application.

This event is useful when:

* You want to build your own fullscreen button in the parent application
* You need to keep Omni's presentation state in sync with native browser fullscreen
* You want to provide a consistent fullscreen experience across your application

<Warning>
  The `postMessage` protocol does not carry user activation, so sending this event alone only applies Omni's CSS overlay presentation. To enable true browser fullscreen, call `iframeElement.requestFullscreen()` in your own click handler first, then post `fullscreen:set` to sync Omni's presentation styling.
</Warning>

```json theme={null}
{
  "name": "fullscreen:set",
  "payload": {
    "isFullScreen": true
  }
}
```

## Properties

<ParamField path="isFullScreen" type="boolean" required>
  The fullscreen presentation state to apply. Accepts one of:

  * `true` - Activates fullscreen presentation mode
  * `false` - Deactivates fullscreen presentation mode
</ParamField>

## Example

This example demonstrates a parent-controlled fullscreen implementation that coordinates native browser fullscreen with Omni's presentation state:

```html theme={null}
<iframe id="omni" src="https://embed.example.omni.co/dashboards/abc123" allow="fullscreen" allowfullscreen></iframe>
<button id="fullscreen-btn">Full screen</button>

<script>
  const iframe = document.getElementById('omni')

  document.getElementById('fullscreen-btn').addEventListener('click', () => {
    // Native fullscreen needs the click's user activation, so the parent
    // requests it on the iframe element itself...
    iframe.requestFullscreen()
    // ...and tells Omni to apply its presentation styling.
    iframe.contentWindow.postMessage(
      { name: 'fullscreen:set', payload: { isFullScreen: true } },
      'https://embed.example.omni.co'
    )
  })

  // Keep the parent in sync however fullscreen was entered or exited
  // (Omni's own button, keyboard shortcut, Esc).
  window.addEventListener('message', ({ data }) => {
    if (data?.source === 'omni' && data.name === 'fullscreen:changed') {
      console.log('fullscreen:', data.payload.isFullScreen)
      if (!data.payload.isFullScreen && document.fullscreenElement) {
        document.exitFullscreen()
      }
    }
  })
</script>
```