OverlayWindow.swift

import Cocoa
import SwiftUI

class OverlayWindow: NSWindow {

    private var initialLocation: NSPoint = .zero

    override var canBecomeKey: Bool { true }

    init(view: NSView) {
        let screenSize = NSScreen.main?.frame ?? .zero
        let frame = CGRect(
            x: screenSize.midX - 150,
            y: screenSize.midY - 100,
            width: 300,
            height: 180
        )

        super.init(
            contentRect: frame,
            styleMask: [.borderless],
            backing: .buffered,
            defer: false
        )

        isOpaque = false
        backgroundColor = .clear
        level = .floating
        hasShadow = false
        ignoresMouseEvents = false
        collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]

        contentView = view
        makeKeyAndOrderFront(nil)
    }

    // Drag to move
    override func mouseDown(with event: NSEvent) {
        initialLocation = event.locationInWindow
    }

    override func mouseDragged(with event: NSEvent) {
        var newOrigin = frame.origin
        let currentLocation = event.locationInWindow

        newOrigin.x += currentLocation.x - initialLocation.x
        newOrigin.y += currentLocation.y - initialLocation.y

        setFrameOrigin(newOrigin)
    }
}