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# NSVisualEffectView.Material.underWindowBackground

The material to show under a window’s background.

```
case underWindowBackground
```

## Discussion

Use this material on a visual effect view with a [`blendingMode`](/documentation/AppKit/NSVisualEffectView/blendingMode-swift.property) of [`NSVisualEffectView.BlendingMode.behindWindow`](/documentation/AppKit/NSVisualEffectView/BlendingMode-swift.enum/behindWindow) to create a sense of peeking through the back of the window. This effect creates an illusion that the background of the window has peeled away to reveal what’s under it.

---

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