---
title: "acceptsFirstMouse(for:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nsslider/acceptsfirstmouse(for:)"
---

# acceptsFirstMouse(for:)

Returns a Boolean value indicating whether a mouse-down event both activates the window and starts dragging the slider’s knob.

## Declaration

```swift
func acceptsFirstMouse(for event: NSEvent?) -> Bool
```

## Parameters

- `event`: The mouse-down event.

## Return Value

Return Value true if the receiver accepts the first mouse-down event; otherwise, false. Returns true by default.

## Discussion

Discussion If you want the slider to wait for its own mouse-down event, you must override this method.