diff --git a/src/Makefile.am b/src/Makefile.am
index 5f5a0b4..d19f7b2 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -19,7 +19,7 @@ EXTRA_DIST = \
 AM_CPPFLAGS = -DG_LOG_DOMAIN=\"Astrognome\" -DLOCALEDIR=\"$(localedir)\" -DPKGDATADIR=\"$(pkgdatadir)\"
 bin_PROGRAMS = astrognome
 
-astrognome_SOURCES = ag-app.c astrognome.c $(BUILT_SOURCES)
+astrognome_SOURCES = ag-app.c ag-window.c astrognome.c $(BUILT_SOURCES)
 astrognome_LDADD = $(SWE_GLIB_LIBS) $(GTK_LIBS) $(top_builddir)/libgd/libgd.la
 astrognome_LDFLAGS = -rdynamic
 astrognome_CFLAGS = $(SWE_GLIB_CFLAGS) $(CFLAGS) $(GTK_CFLAGS) -Wall -I$(top_srcdir)/libgd
diff --git a/src/ag-window.c b/src/ag-window.c
new file mode 100644
index 0000000..c68dd39
--- /dev/null
+++ b/src/ag-window.c
@@ -0,0 +1,114 @@
+#include <libgd/gd.h>
+
+#include "ag-app.h"
+#include "ag-window.h"
+
+struct _AgWindowPrivate {
+    GtkWidget *grid;
+    GtkWidget *header_bar;
+    GtkWidget *notebook;
+    GtkBuilder *builder;
+};
+
+G_DEFINE_TYPE(AgWindow, ag_window, GTK_TYPE_APPLICATION_WINDOW);
+
+#define GET_PRIVATE(instance) (G_TYPE_INSTANCE_GET_PRIVATE((instance), AG_TYPE_WINDOW, AgWindowPrivate))
+
+static void
+gear_menu_cb(GSimpleAction *action, GVariant *parameter, gpointer user_data)
+{
+    GVariant *state;
+
+    state = g_action_get_state(G_ACTION(action));
+    g_action_change_state(G_ACTION(action), g_variant_new_boolean(!g_variant_get_boolean(state)));
+
+    g_variant_unref(state);
+}
+
+static void
+close_cb(GSimpleAction *action, GVariant *parameter, gpointer user_data)
+{
+    AgWindow *window = user_data;
+
+    // TODO: Save unsaved changes!
+    gtk_widget_destroy(GTK_WIDGET(window));
+}
+
+static GActionEntry win_entries[] = {
+    { "close",     close_cb,     NULL, NULL,    NULL },
+    { "gear-menu", gear_menu_cb, NULL, "false", NULL },
+};
+
+static void
+ag_window_init(AgWindow *window)
+{
+    AgWindowPrivate *priv;
+    GtkAccelGroup *accel_group;
+    GError *err = NULL;
+
+    window->priv = priv = GET_PRIVATE(window);
+
+    gtk_window_set_hide_titlebar_when_maximized(GTK_WINDOW(window), TRUE);
+
+    priv->builder = gtk_builder_new();
+
+    if (!gtk_builder_add_from_resource(priv->builder, "/eu/polonkai/gergely/astrognome/astrognome.ui", &err)) {
+        g_error("Cannot add resource to builder: '%s'", (err) ? err->message : "unknown error");
+        g_clear_error(&err);
+    }
+
+    priv->grid = gtk_grid_new();
+    gtk_widget_show(priv->grid);
+
+    gtk_container_add(GTK_CONTAINER(window), priv->grid);
+
+    g_action_map_add_action_entries(G_ACTION_MAP(window), win_entries, G_N_ELEMENTS(win_entries), window);
+
+    accel_group = gtk_accel_group_new();
+    gtk_window_add_accel_group(GTK_WINDOW(window), accel_group);
+}
+
+static void
+ag_window_class_init(AgWindowClass *klass)
+{
+    g_type_class_add_private(klass, sizeof(AgWindowPrivate));
+}
+
+static void
+window_populate(AgWindow *window)
+{
+    AgWindowPrivate *priv = window->priv;
+    GtkWidget *menu_button;
+    GObject *menu;
+
+    priv->header_bar = gd_header_bar_new();
+    menu_button = gd_header_menu_button_new();
+    gd_header_button_set_symbolic_icon_name(GD_HEADER_BUTTON(menu_button), "emblem-system-symbolic");
+    gtk_actionable_set_action_name(GTK_ACTIONABLE(menu_button), "win.gear-menu");
+
+    gd_header_bar_pack_end(GD_HEADER_BAR(priv->header_bar), menu_button);
+
+    gtk_grid_attach(GTK_GRID(priv->grid), priv->header_bar, 0, 0, 1, 1);
+
+    menu = gtk_builder_get_object(priv->builder, "window-menu");
+    gtk_menu_button_set_menu_model(GTK_MENU_BUTTON(menu_button), G_MENU_MODEL(menu));
+
+    gtk_widget_show_all(priv->grid);
+}
+
+GtkWidget *
+ag_window_new(AgApp *app)
+{
+    AgWindow *window;
+
+    window = g_object_new(AG_TYPE_WINDOW, NULL);
+
+    gtk_window_set_application(GTK_WINDOW(window), GTK_APPLICATION(app));
+
+    window_populate(window);
+
+    gtk_window_set_icon_name(GTK_WINDOW(window), "astrognome");
+
+    return GTK_WIDGET(window);
+}
+
diff --git a/src/ag-window.h b/src/ag-window.h
new file mode 100644
index 0000000..a1780c4
--- /dev/null
+++ b/src/ag-window.h
@@ -0,0 +1,35 @@
+#ifndef __AG_WINDOW_H__
+#define __AG_WINDOW_H__
+
+#include <gtk/gtk.h>
+#include "ag-app.h"
+
+G_BEGIN_DECLS
+
+#define AG_TYPE_WINDOW         (ag_window_get_type())
+#define AG_WINDOW(o)           (G_TYPE_CHECK_INSTANCE_CAST((o), AG_TYPE_WINDOW, AgWindow))
+#define AG_WINDOW_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST((k), AG_TYPE_WINDOW, AgWindowClass))
+#define AG_IS_WINDOW(o)        (G_TYPE_CHECK_INSTANCE_TYPE((o), AG_TYPE_WINDOW))
+#define AG_IS_WINDOW_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE((k), AG_TYPE_WINDOW))
+#define AG_WINDOW_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS((o), AG_TYPE_WINDOW, AgWindowClass))
+
+typedef struct _AgWindow AgWindow;
+typedef struct _AgWindowClass AgWindowClass;
+typedef struct _AgWindowPrivate AgWindowPrivate;
+
+struct _AgWindow {
+    GtkApplicationWindow parent_instance;
+    AgWindowPrivate *priv;
+};
+
+struct _AgWindowClass {
+    GtkApplicationWindowClass parent_class;
+};
+
+GType ag_window_get_type(void) G_GNUC_CONST;
+GtkWidget *ag_window_new(AgApp *app);
+
+G_END_DECLS
+
+#endif /* __AG_WINDOW_H__ */
+
diff --git a/src/astrognome.ui b/src/astrognome.ui
index 29f48aa..3c9841a 100644
--- a/src/astrognome.ui
+++ b/src/astrognome.ui
@@ -28,6 +28,20 @@
       </item>
     </section>
   </menu>
+  <menu id="window-menu">
+    <section>
+      <item>
+        <attribute name="label" translatable="yes">Chart</attribute>
+        <attribute name="action">win.tab-chart</attribute>
+        <attribute name="accel">F5</attribute>
+      </item>
+      <item>
+        <attribute name="label" translatable="yes">Aspects</attribute>
+        <attribute name="action">win.tab-aspects</attribute>
+        <attribute name="accel">F9</attribute>
+      </item>
+    </section>
+  </menu>
   <object class="GtkActionGroup" id="actions">
     <property name="accel_group">accels</property>
     <child>