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# NSView.TrackingRectTag

This type describes the rectangle used to track the mouse.

```
typealias TrackingRectTag = Int
```

## Discussion

If the value of this type is 0, it is invalid. See the methods [`addTrackingRect(_:owner:userData:assumeInside:)`](/documentation/AppKit/NSView/addTrackingRect(_:owner:userData:assumeInside:)) and [`removeTrackingRect(_:)`](/documentation/AppKit/NSView/removeTrackingRect(_:)).

---

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