---
title: "window(_:willUseFullScreenContentSize:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nswindowdelegate/window(_:willusefullscreencontentsize:)"
---

# window(_:willUseFullScreenContentSize:)

Called to allow the delegate to modify the full-screen content size.

## Declaration

```swift
@MainActor optional func window(_ window: NSWindow, willUseFullScreenContentSize proposedSize: NSSize) -> NSSize
```

## Parameters

- `window`: The window to enter to full-screen mode.
- `proposedSize`: The proposed window size.

## Return Value

Return Value The window size to use when displaying content size.

## See Also

### Managing Full-Screen Presentation

- [window(_:willUseFullScreenPresentationOptions:)](appkit/nswindowdelegate/window(_:willusefullscreenpresentationoptions:).md)
- [windowWillEnterFullScreen(_:)](appkit/nswindowdelegate/windowwillenterfullscreen(_:).md)
- [windowDidEnterFullScreen(_:)](appkit/nswindowdelegate/windowdidenterfullscreen(_:).md)
- [windowWillExitFullScreen(_:)](appkit/nswindowdelegate/windowwillexitfullscreen(_:).md)
- [windowDidExitFullScreen(_:)](appkit/nswindowdelegate/windowdidexitfullscreen(_:).md)