---
title: "splitView(_:additionalEffectiveRectOfDividerAt:)"
framework: appkit
role: symbol
role_heading: Instance Method
path: "appkit/nssplitviewdelegate/splitview(_:additionaleffectiverectofdividerat:)"
---

# splitView(_:additionalEffectiveRectOfDividerAt:)

Allows the delegate to return an additional rectangle where mouse clicks can initiate divider dragging.

## Declaration

```swift
@MainActor optional func splitView(_ splitView: NSSplitView, additionalEffectiveRectOfDividerAt dividerIndex: Int) -> NSRect
```

## Parameters

- `splitView`: The split view that sends the message.
- `dividerIndex`: The index of the divider.

## Return Value

Return Value An additional rectangle, in the coordinate system that splitView defines, where mouse clicks can initiate divider dragging. Returning NSZeroRect indicates no additional dragging rectangle is necessary.

## Discussion

Discussion If a split view has no delegate, or if its delegate doesn’t respond to this message, only mouse clicks within the effective frame of a divider initiate divider dragging.

## See Also

### Configuring and Drawing View Dividers

- [splitView(_:effectiveRect:forDrawnRect:ofDividerAt:)](appkit/nssplitviewdelegate/splitview(_:effectiverect:fordrawnrect:ofdividerat:).md)
- [splitView(_:shouldHideDividerAt:)](appkit/nssplitviewdelegate/splitview(_:shouldhidedividerat:).md)