I'm attempting to create a macOS application that has a sidebar, and I'd like to be able to use the new .sidebarTrackingSeparator toolbar item. However, it's not accessible as part of ToolbarItemPlacement, and the following code:
NSApp.keyWindow?.toolbar?.insertItem(withItemIdentifier: .sidebarTrackingSeparator, at: 0)
places it, but the item isn't visible.
Is there any way to place a button in the toolbar such that it's visible on top of the sidebar like Xcode's left-collapse item?