window.kt

Window(
    // ....
    undecorated = true, // kills the OS title bar
    transparent = true, // makes the window background see-through
    resizable = false,
    alwaysOnTop = true,
    // ....
) {
    WindowDraggableArea { // since there's no title bar to drag, this wraps the content and handles it
        App()
    }
}