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# outlineView(_:mouseDownInHeaderOf:)

Sent to the delegate whenever the mouse button is clicked in `outlineView` while the cursor is in a column header `tableColumn`.

```
@MainActor optional func outlineView(_ outlineView: NSOutlineView, mouseDownInHeaderOf tableColumn: NSTableColumn)
```

## Parameters

`outlineView`

The outline view that sent the message.

`tableColumn`

The table column.

---

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