diff --git a/src/Makefile.am b/src/Makefile.am
index 7f0e672..153d8b9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -12,11 +12,12 @@ BUILT_SOURCES = \
 				$(NULL)
 
 astrognome_source_files = \
-						  ag-app.c      \
-						  ag-window.c   \
-						  ag-chart.c    \
-						  ag-settings.c \
-						  astrognome.c  \
+						  ag-app.c         \
+						  ag-window.c      \
+						  ag-chart.c       \
+						  ag-settings.c    \
+						  ag-preferences.c \
+						  astrognome.c     \
 						  $(NULL)
 
 EXTRA_DIST = \
diff --git a/src/ag-app.c b/src/ag-app.c
index b010f4d..fff9627 100644
--- a/src/ag-app.c
+++ b/src/ag-app.c
@@ -2,6 +2,7 @@
 #include "ag-app.h"
 #include "ag-window.h"
 #include "ag-chart.h"
+#include "ag-preferences.h"
 #include "config.h"
 #include "astrognome.h"
 
@@ -62,7 +63,11 @@ new_window_cb(GSimpleAction *action, GVariant *parameter, gpointer user_data)
 static void
 preferences_cb(GSimpleAction *action, GVariant *parameter, gpointer user_data)
 {
-    //ag_preferences_show_dialog();
+    AgApp *app = AG_APP(user_data);
+    GtkWindow *window;
+
+    window = ag_app_peek_first_window(app);
+    ag_preferences_show_dialog(window);
 }
 
 static void
diff --git a/src/ag-preferences.c b/src/ag-preferences.c
new file mode 100644
index 0000000..5615d4a
--- /dev/null
+++ b/src/ag-preferences.c
@@ -0,0 +1,77 @@
+#include <gtk/gtk.h>
+
+#include "ag-settings.h"
+#include "ag-preferences.h"
+
+static GtkWidget *prefs_dialog = NULL;
+
+typedef struct _AgPreferencesPrivate {
+    GtkCheckButton *maximized;
+    AgSettings *settings;
+} AgPreferencesPrivate;
+
+G_DEFINE_TYPE_WITH_PRIVATE(AgPreferences, ag_preferences, GTK_TYPE_DIALOG);
+
+static void
+ag_preferences_finalize(GObject *gobject)
+{
+    AgPreferencesPrivate *priv;
+
+    priv = ag_preferences_get_instance_private(AG_PREFERENCES(gobject));
+
+    g_clear_object(&priv->settings);
+
+    G_OBJECT_CLASS(ag_preferences_parent_class)->finalize(gobject);
+}
+
+static void
+ag_preferences_response(GtkDialog *dlg, gint response_id)
+{
+    gtk_widget_destroy(GTK_WIDGET(dlg));
+}
+
+static void
+ag_preferences_class_init(AgPreferencesClass *klass)
+{
+    GObjectClass   *object_class = G_OBJECT_CLASS(klass);
+    GtkWidgetClass *widget_class = GTK_WIDGET_CLASS(klass);
+    GtkDialogClass *dialog_class = GTK_DIALOG_CLASS(klass);
+
+    object_class->finalize = ag_preferences_finalize;
+    dialog_class->response = ag_preferences_response;
+
+    gtk_widget_class_set_template_from_resource(widget_class, "/eu/polonkai/gergely/astrognome/ag-preferences.ui");
+    gtk_widget_class_bind_template_child_private(widget_class, AgPreferences, maximized);
+}
+
+static void
+ag_preferences_init(AgPreferences *prefs)
+{
+    AgPreferencesPrivate *priv;
+    GSettings            *settings_window;
+
+    priv = ag_preferences_get_instance_private(prefs);
+    gtk_widget_init_template(GTK_WIDGET(prefs));
+
+    priv->settings = ag_settings_get();
+
+    settings_window = ag_settings_peek_window_settings(priv->settings);
+    g_settings_bind(settings_window, "maximized", priv->maximized, "active", G_SETTINGS_BIND_DEFAULT);
+}
+
+void
+ag_preferences_show_dialog(GtkWindow *parent)
+{
+    g_return_if_fail(GTK_IS_WINDOW(parent));
+
+    if (prefs_dialog == NULL) {
+        prefs_dialog = GTK_WIDGET(g_object_new(AG_TYPE_PREFERENCES, NULL));
+        g_signal_connect(prefs_dialog, "destroy", G_CALLBACK(gtk_widget_destroyed), &prefs_dialog);
+    }
+
+    if (parent != gtk_window_get_transient_for(GTK_WINDOW(prefs_dialog))) {
+        gtk_window_set_transient_for(GTK_WINDOW(prefs_dialog), parent);
+    }
+
+    gtk_window_present(GTK_WINDOW(prefs_dialog));
+}
diff --git a/src/ag-preferences.h b/src/ag-preferences.h
new file mode 100644
index 0000000..686d9e7
--- /dev/null
+++ b/src/ag-preferences.h
@@ -0,0 +1,32 @@
+#ifndef __AG_PREFERENCES_H__
+#define __AG_PREFERENCES_H__
+
+#include <gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+#define AG_TYPE_PREFERENCES         (ag_preferences_get_type())
+#define AG_PREFERENCES(o)           (G_TYPE_CHECK_INSTANCE_CAST((o), AG_TYPE_PREFERENCES, AgPreferences))
+#define AG_PREFERENCES_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST((k), AG_TYPE_PREFERENCES, AgPreferencesClass))
+#define AG_IS_PREFERENCES(o)        (G_TYPE_CHECK_INSTANCE_TYPE((o), AG_TYPE_PREFERENCES))
+#define AG_IS_PREFERENCES_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE((k), AG_TYPE_PREFERENCES))
+#define AG_PREFERENCES_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS((o), AG_TYPE_PREFERENCES, AgPreferencesClass))
+
+typedef struct _AgPreferences        AgPreferences;
+typedef struct _AgPreferencesClass   AgPreferencesClass;
+
+struct _AgPreferences {
+    GtkDialog parent;
+};
+
+struct _AgPreferencesClass {
+    GtkDialogClass parent_class;
+};
+
+GType ag_preferences_get_type(void);
+
+void ag_preferences_show_dialog(GtkWindow *parent);
+
+G_END_DECLS
+
+#endif /* __AG_PREFERENCES_H__ */
diff --git a/src/ag-preferences.ui b/src/ag-preferences.ui
new file mode 100644
index 0000000..1f5a2a7
--- /dev/null
+++ b/src/ag-preferences.ui
@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- Generated with glade 3.18.3 -->
+<interface>
+  <requires lib="gtk+" version="3.12"/>
+  <template class="AgPreferences" parent="GtkDialog">
+    <property name="can_focus">False</property>
+    <property name="type_hint">normal</property>
+    <child internal-child="vbox">
+      <object class="GtkBox" id="dialog-vbox1">
+        <property name="can_focus">False</property>
+        <property name="orientation">vertical</property>
+        <property name="spacing">2</property>
+        <child internal-child="action_area">
+          <object class="GtkButtonBox" id="dialog-action_area1">
+            <property name="can_focus">False</property>
+            <property name="layout_style">end</property>
+            <child>
+              <placeholder/>
+            </child>
+            <child>
+              <placeholder/>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="pack_type">end</property>
+            <property name="position">0</property>
+          </packing>
+        </child>
+        <child>
+          <object class="GtkGrid" id="grid2">
+            <property name="visible">True</property>
+            <property name="can_focus">False</property>
+            <child>
+              <object class="GtkCheckButton" id="maximized">
+                <property name="label" translatable="yes">New windows start maximized</property>
+                <property name="visible">True</property>
+                <property name="can_focus">True</property>
+                <property name="receives_default">False</property>
+                <property name="xalign">0</property>
+                <property name="draw_indicator">True</property>
+              </object>
+              <packing>
+                <property name="left_attach">0</property>
+                <property name="top_attach">0</property>
+              </packing>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">True</property>
+            <property name="position">1</property>
+          </packing>
+        </child>
+      </object>
+    </child>
+  </template>
+</interface>
diff --git a/src/ag.gresource.xml b/src/ag.gresource.xml
index 6466ba3..61f3916 100644
--- a/src/ag.gresource.xml
+++ b/src/ag.gresource.xml
@@ -2,5 +2,6 @@
 <gresources>
   <gresource prefix="/eu/polonkai/gergely/astrognome">
     <file>astrognome.ui</file>
+    <file>ag-preferences.ui</file>
   </gresource>
 </gresources>