added custom main menu

src/MainMenu.js

@@ -0,0 +1,27 @@
+"use strict";
+
+const {Menu} = require("electron");
+
+class MainMenu {
+	constructor(app) {
+		this.app  = app;
+		this.menu = null;
+		this.buildItems();
+		Menu.setApplicationMenu(this.menu);
+	}
+
+	buildItems() {
+		const template = [
+			...(process.platform === "darwin" ? [{
+				role : "appMenu"
+			}] : []),
+			{
+				role : "windowMenu"
+			}
+		];
+
+		this.menu = Menu.buildFromTemplate(template);
+	}
+}
+
+module.exports = MainMenu;