Horizontal and vertical nested scroll views
<p>My view contains a horizontally scrolling Scroll View containing multiple vertically scrolling Table Views. </p>

<p>See diagram:</p>

<p><a href="https://i.stack.imgur.com/1pWDl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1pWDl.png" alt="enter image description here"></a></p>

<p>However, the Table Views are blocking horizontal scrolling in the Scroll View when the cursor is on them.</p>

<p>How can I allow the scroll to pass on to the superview?</p>

<hr>

<p>Code for Application</p>

<pre><code>@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

     @IBOutlet weak var window: NSWindow!
    var viewController: ViewController!

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        viewController = ViewController(nibName: "ViewController", bundle: nil)  
        viewController.view.translatesAutoresizingMaskIntoConstraints = false
        window.contentView!.addSubview(viewController.view)
        //...
    }
    //...
}
</code></pre>

<p>View Controller</p>

<pre><code>class ViewController: NSViewController {

    @IBOutlet weak var scrollView: NSScrollView!
    //...

    func addListView(listPath: String) {
        let listView = ListViewController(nibName: "ListView", bundle: nil)
        listView!.listPath = listPath

        listView!.view.translatesAutoresizingMaskIntoConstraints = false
        scrollView.contentView.addSubview(listView!.view)
        //...
    }
    //...
}
</code></pre>

<p>List View</p>

<pre><code>class ListViewController: NSViewController {

    @IBOutlet weak var itemsTitleView: NSTextField!
    @IBOutlet weak var itemsTableView: MyTableView!
    //...
}
</code></pre>

<p>TableView</p>

<pre><code>class MyTableView: NSTableView {

    override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)

        // Drawing code here.
    }

    var mainScrollView: NSScrollView? {
        let app = NSApplication.sharedApplication()
        let delegate = app.delegate as! AppDelegate
        return delegate.viewController.scrollView
}

    override func mouseDown(theEvent: NSEvent) {
        // do nothing
    }

    override func scrollWheel(theEvent: NSEvent) {
        if theEvent.scrollingDeltaY == 0 {
            // It's a horizontal scroll -&gt; redirect it
            if let tableScrollView = enclosingScrollView, mainScrollView = mainScrollView {
                mainScrollView.scrollWheel(theEvent)
            }
        } else {
            // It's a vertical scroll -&gt; behave normally
            super.scrollWheel(theEvent)
        }
    }

}
</code></pre>