Gives you a chance to modify the window as it is constructed. Intended to let you add custom menu options.

import arsd.terminal;
integratedTerminalEmulatorConfiguration.menuExtensionsConstructor = (TerminalEmulatorWindow window) {
	import arsd.minigui; // for the menu related UDAs
	class Commands {
		@menu("Help") {
			void Topics() {
				auto window = new Window(); // make a help window of some sort
				window.show();
			}

			@separator

			void About() {
				messageBox("My Application v 1.0");
			}
		}
	}
	window.setMenuAndToolbarFromAnnotatedCode(new Commands());
};