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# testPart(_:)

Returns the part that would be hit by a mouse-down event at `aPoint` (expressed in the window’s coordinate system).

```
func testPart(_ point: NSPoint) -> NSScroller.Part
```

## Discussion

See [`NSScroller.Part`](/documentation/AppKit/NSScroller/Part) for a list of possible return values. In macOS 10.7 and later, this method no longer returns [`NSScroller.Part.incrementLine`](/documentation/AppKit/NSScroller/Part/incrementLine) or [`NSScroller.Part.decrementLine`](/documentation/AppKit/NSScroller/Part/decrementLine).

Note the interpretations of `NSScrollerDecrementPage` and `NSScrollerIncrementPage`. The actual part of a scroller that causes page-by-page scrolling varies, so as a convenience these part codes refer to useful parts different from the scroll buttons.

## See Also

[`hitPart`](/documentation/AppKit/NSScroller/hitPart)

A part code indicating the manner in which the scrolling should be performed.


---

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