@main
struct SuperCoolApp: App {

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .settings {
            // 1.1 - The "General" settings tab.
            SettingsTab(.init("General", systemSymbol: .gearshape), id: "general-tab") {
                // 1.2 - The "General" > "Appearance" settings subtab.
                SettingsSubtab(.init("Appearance", systemSymbol: .circleLefthalfFilled), id: "appearance") {
                    AppearanceSettings()
                }
                // 1.2 - The "General" > "Composer" settings subtab.
                SettingsSubtab(.init("Composer", systemSymbol: .person), id: "composer") {
                    ComposerSettings()
                }
            }

            // 1.3 - An extension for the "General" settings tab.
            SettingsTab(.extend(id: "general-tab"), id: "general-tab-extension") {
                // 1.4 - The "General" settings subtab for no selection.
                SettingsSubtab(.noSelection, id: "no-selection") {
                    NoSelectionInformation()
                }
            }

            // 1.1 - The "Themes" settings tab.
            SettingsTab(.init("Themes", systemSymbol: .paintbrush)) {
                for theme in themes {
                    // 1.2 - A "Themes" > "THEME_NAME" settings subtab for each theme.
                    SettingsSubtab(.init(theme.title, systemSymbol: .paintbrush), id: theme.id) {

                    }
                }
            }
            // 2.1 - The "+" and "-" buttons in the sidebar's toolbar.
            .standardActions {
                themes.append(.init())
            } remove: { index in
                if let index {
                    themes.remove(at: index)
                }
            }

        }
    }

}