Clear / Transparent background for NavigationSplitView

[mikechambers]

I am trying to use the library to set the background of a navigation split view to be clear / transparent on MacOS

Looking at code here, which does it:
https://stackoverflow.com/questions/74838683/is-there-any-way-to-make-navigationsplitviews-side-bar-with-clear-background

        .introspectSplitViewController { controller in

            controller.viewControllers[0].view.backgroundColor = UIColor.clear
            
            for subview in controller.viewControllers[0].view.subviews {
                subview.backgroundColor = UIColor.clear
                for innerSubview in subview.subviews {
                    innerSubview.backgroundColor = UIColor.clear
                    for innerInnerSubview in innerSubview.subviews {
                        innerInnerSubview.backgroundColor = UIColor.clear
                    }
                }
            }
          }

But this seems to be out of date now, and im having trouble finding how to set the background color to clear (Im not as familiar with UIKit). Any tips, suggestions or pointers?

I also saw this post:
https://github.com/davdroman/NavigationSplitViewRemoveBackgrounds/blob/main/NavigationSplitViewRemoveBackgrounds.swiftpm/MyApp.swift

but that is iOS and im having trouble getting it working on MacOs

[mikechambers]

ok. Here is what I have thus far:

			.introspect(.navigationSplitView, on: .macOS(.v14)) { split in
				
				let c = split.delegate as! NSViewController
				let removeBackgrounds = {
					
					c.children.forEach { controller in
						controller.parent?.view.wantsLayer = true
						controller.parent?.view.layer?.backgroundColor = bgColor
						controller.view.clearBackgrounds()
					}
				}
				removeBackgrounds() // run now...
				DispatchQueue.main.async(execute: removeBackgrounds) // ... and on the next run loop pass
			}

and

let bgColor = NSColor.clear.cgColor
private extension NSView {
	func clearBackgrounds() {
		wantsLayer = true
		layer?.backgroundColor = bgColor
		for subview in subviews {
			subview.clearBackgrounds()
		}
	}
}

I i set the color to something like blue, then everything except title bar is blue:

However, if I set to clear, it doesnt work for sidebar / titlebar:

(The image is the background in a zstack)

I feel like im getting close, just missing something obvious.

btw, I am able to set the opacity on the views, but then that also sets the opacity for the content.

Edit I posted a simplified project here with current code:
https://github.com/mikechambers/TransparentNavigationSplitViewExample