Added tabs, and pained

data/org.gnome.Usage.desktop

+[Desktop Entry]
+Name=GNOME Usage
+Comment=View current processes and monitor system state
+Categories=GNOME;GTK;System;Monitor;
+Exec=hello-again
+Icon=application-default-icon
+Terminal=false
+Type=Application
+X-GNOME-Gettext-Domain=gnome-usage
+Keywords=Monitor;System;Process;CPU;Memory;Network;History;Usage;Performance;Task;Manager;

gnome-usage.avprj

@@ -6,14 +6,29 @@ project_name: gnome-usage
 
 *vala_binary: src/gnome-usage
 *version: 0.0.1
+*vala_check_package: atk
+*vala_check_package: cairo
+*vala_check_package: gdk-3.0
+*vala_check_package: gdk-pixbuf-2.0
+*vala_check_package: gio-2.0
 *vala_check_package: glib-2.0
+*vala_check_package: gobject-2.0
+*vala_check_package: gtk+-3.0
+*vala_check_package: pango
+*vala_check_package: x11
+*vala_source: application.vala
 *vala_source: gnome-usage.vala
+*vala_source: window.vala
 
 *po: po
 
 *translate: vala src/gnome-usage.vala
+*translate: vala src/application.vala
+*translate: vala src/window.vala
 
 *data: data/local
 
 *doc: doc
 
+*desktop: data/org.gnome.Usage.desktop
+

src/application.vala

+using Gtk;
+
+namespace Usage {
+
+    public class Application : Gtk.Application {
+
+        private Window window;
+
+        public Application () {
+            application_id = "org.gnome.usage";
+        }
+
+        public override void activate () {
+            window = new Window (this);
+            window.show_all();
+        }
+    }
+}

src/gnome-usage.vala

 // project version=0.0.1
-int main (string[] args) {
-    print("Hi, I will new GNOME Usage!\n");
-    return 0;
+
+public static int main (string[] args) {
+
+    Intl.bindtextdomain(Constants.GETTEXT_PACKAGE, Path.build_filename(Constants.DATADIR,"locale"));
+    Intl.setlocale (LocaleCategory.ALL, "");
+    Intl.textdomain(Constants.GETTEXT_PACKAGE);
+    Intl.bind_textdomain_codeset(Constants.GETTEXT_PACKAGE, "utf-8");
+
+    stdout.printf ("Not Translatable string");
+    stdout.printf (_("Translatable string!"));
+
+    var application = new Usage.Application ();
+    return application.run (args);
 }

src/window.vala

+namespace Usage
+{
+    public class Window : Gtk.ApplicationWindow
+    {
+        public Window (Gtk.Application application)
+        {
+            GLib.Object (application: application);
+            this.destroy.connect(Gtk.main_quit);
+
+            this.set_default_size(800, 500);
+            this.window_position = Gtk.WindowPosition.CENTER;
+
+			var stack = new Gtk.Stack();
+			stack.set_transition_type(Gtk.StackTransitionType.SLIDE_LEFT_RIGHT);
+    		stack.set_transition_duration(700);
+
+    		var label1 = new Gtk.Label("Page 1 Content.");
+    		var label5 = new Gtk.Label("Page 5 Content.");
+    		var paned = new Gtk.Paned(Gtk.Orientation.HORIZONTAL);
+    		paned.add1(label1);
+    		paned.add2(label5);
+    		stack.add_titled(paned, "page-1", "Performance");
+    		var label2 = new Gtk.Label("Page 2 Content.");
+    		stack.add_titled(label2, "page-2", "Data");
+    		var label3 = new Gtk.Label("Page 3 Content.");
+    		stack.add_titled(label3, "page-3", "Storage");
+    		var label4 = new Gtk.Label("Page 4 Content.");
+    		stack.add_titled(label4, "page-4", "Power");
+
+			var stack_switcher = new Gtk.StackSwitcher();
+			stack_switcher.halign = Gtk.Align.CENTER;
+            stack_switcher.stack = stack;
+            stack_switcher.set_stack(stack);
+
+            var headerbar = new Gtk.HeaderBar();
+            headerbar.show_close_button = true;
+			headerbar.set_custom_title(stack_switcher);
+            set_titlebar(headerbar);
+
+            this.add(stack);
+        }
+    }
+}