Hide Traffic Light Buttons in NSWindow Without Removing Resize Functionality

I noticed that in macOS’s dark mode, a window without a visible title bar won’t draw a light border. It will draw a dark/black border, unlike all the other windows, and thus be a lot less visible than it needs to be.

So for a floating helper window, I had to make the title bar visible, and then hide all traffic light buttons in the window’s top-left corner:

class WindowController: NSWindowController {
    override func windowDidLoad() {

        // Hide the textual window title.
        self.window?.titleVisibility = .hidden
        self.window?.styleMask = []

        // We need a textured window to get the correct border color.

        // Making the window resizable will show the traffic lights automatically ...
        // ... so hide all traffic light buttons manually:
        self.window?.standardWindowButton(.closeButton)?.isHidden = true
        self.window?.standardWindowButton(.miniaturizeButton)?.isHidden = true
        self.window?.standardWindowButton(.zoomButton)?.isHidden = true
        self.window?.standardWindowButton(.fullScreenButton)?.isHidden = true

Until today, I didn’t know that NSWindow even has standardWindowButton(_:) that you can use to get to the traffic lights!

With this setup, you get resizability of the window, which would usually result in at least 1 traffic light to show, and a full-sized content view without any visible title bar at all.

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