Description: Hide Headerbar window buttons and title when running in Unity
 and the window is maximized.
 Plus define the "toolbar-mode" style class on these maximized bars.
Author: Marco Trevisan <marco.trevisan@canonical.com>
Bug-Ubuntu: https://launchpad.net/bugs/1515810

Index: gtk+3.0-3.18.8/gtk/gtkheaderbar.c
===================================================================
--- gtk+3.0-3.18.8.orig/gtk/gtkheaderbar.c
+++ gtk+3.0-3.18.8/gtk/gtkheaderbar.c
@@ -31,6 +31,10 @@
 
 #include <string.h>
 
+#ifdef GDK_WINDOWING_X11
+#include "x11/gdkx.h"
+#endif
+
 /**
  * SECTION:gtkheaderbar
  * @Short_description: A box with a centered child
@@ -65,6 +69,7 @@ struct _GtkHeaderBarPrivate
   GtkWidget *custom_title;
   gint spacing;
   gboolean has_subtitle;
+  gboolean unity_environment;
 
   GList *children;
 
@@ -255,7 +260,7 @@ _gtk_header_bar_update_separator_visibil
   gboolean have_visible_at_start = FALSE;
   gboolean have_visible_at_end = FALSE;
   GList *l;
-  
+
   for (l = priv->children; l != NULL; l = l->next)
     {
       Child *child = l->data;
@@ -276,6 +281,76 @@ _gtk_header_bar_update_separator_visibil
     gtk_widget_set_visible (priv->titlebar_end_separator, have_visible_at_end);
 }
 
+static void
+check_headerbar_visbility (GtkHeaderBar *bar)
+{
+  GtkHeaderBarPrivate *priv = gtk_header_bar_get_instance_private (bar);
+  GtkWidget *widget = GTK_WIDGET (bar);
+  GtkWidget *toplevel;
+  gboolean visible = TRUE;
+  gboolean have_visible_child = FALSE;
+  GList *l;
+
+  if (!priv->unity_environment)
+    return;
+
+  for (l = priv->children; l != NULL; l = l->next)
+    {
+      Child *child = l->data;
+
+      if (gtk_widget_get_visible (child->widget))
+        {
+          have_visible_child = TRUE;
+          break;
+        }
+    }
+
+  if (!have_visible_child)
+    {
+      toplevel = gtk_widget_get_toplevel (widget);
+
+      if (GTK_IS_WINDOW (toplevel) && gtk_window_is_maximized (GTK_WINDOW (toplevel)) &&
+          (!priv->title_label || !gtk_widget_get_visible (priv->title_label)) &&
+          (!priv->subtitle_label || !gtk_widget_get_visible (priv->subtitle_label)) &&
+          (!priv->custom_title || !gtk_widget_get_visible (priv->custom_title)))
+        {
+          visible = FALSE;
+        }
+    }
+
+  gtk_widget_set_visible (widget, visible);
+  gtk_widget_queue_draw (widget);
+}
+
+static void
+check_title_visibility (GtkHeaderBar *bar)
+{
+  GtkHeaderBarPrivate *priv = gtk_header_bar_get_instance_private (bar);
+  gboolean visible = TRUE;
+
+  if (!priv->title_label)
+    return;
+
+  if (priv->unity_environment)
+    {
+      GtkWidget *widget = GTK_WIDGET (bar);
+      GtkWidget *toplevel = gtk_widget_get_toplevel (widget);
+
+      if (GTK_IS_WINDOW (toplevel))
+        {
+          GtkWindow *window = GTK_WINDOW (toplevel);
+
+          if (gtk_window_is_maximized (window) &&
+              gtk_window_get_titlebar (window) == widget)
+            {
+              visible = FALSE;
+            }
+        }
+    }
+
+  gtk_widget_set_visible (priv->title_label, visible);
+}
+
 void
 _gtk_header_bar_update_window_buttons (GtkHeaderBar *bar)
 {
@@ -307,6 +382,22 @@ _gtk_header_bar_update_window_buttons (G
     }
 
   priv->titlebar_icon = NULL;
+  window = GTK_WINDOW (gtk_widget_get_toplevel (widget));
+
+  if (priv->unity_environment)
+    {
+      check_title_visibility (bar);
+
+      if (gtk_window_is_maximized (window))
+        {
+          _gtk_header_bar_update_separator_visibility (bar);
+          check_headerbar_visbility (bar);
+          gtk_style_context_add_class (gtk_widget_get_style_context (widget), "toolbar-mode");
+          return;
+        }
+
+      gtk_style_context_remove_class (gtk_widget_get_style_context (widget), "toolbar-mode");
+    }
 
   if (!priv->shows_wm_decorations)
     return;
@@ -324,7 +415,6 @@ _gtk_header_bar_update_window_buttons (G
       layout_desc = g_strdup (priv->decoration_layout);
     }
 
-  window = GTK_WINDOW (gtk_widget_get_toplevel (widget));
 
   if (!shown_by_shell && gtk_window_get_application (window))
     menu = gtk_application_get_app_menu (gtk_window_get_application (window));
@@ -506,6 +596,7 @@ _gtk_header_bar_update_window_buttons (G
   g_free (layout_desc);
 
   _gtk_header_bar_update_separator_visibility (bar);
+  check_headerbar_visbility (bar);
 }
 
 gboolean
@@ -580,6 +671,12 @@ construct_label_box (GtkHeaderBar *bar)
                                       &priv->subtitle_label);
   gtk_header_bar_reorder_css_node (bar, GTK_PACK_START, priv->label_box);
   gtk_widget_set_parent (priv->label_box, GTK_WIDGET (bar));
+
+  g_signal_connect_swapped (priv->title_label, "notify::visible", G_CALLBACK (check_headerbar_visbility), bar);
+  g_signal_connect_swapped (priv->subtitle_label, "notify::visible", G_CALLBACK (check_headerbar_visbility), bar);
+
+  check_title_visibility (bar);
+  check_headerbar_visbility (bar);
 }
 
 static void
@@ -1335,6 +1432,7 @@ gtk_header_bar_set_custom_title (GtkHead
     {
       GtkWidget *custom = priv->custom_title;
 
+      g_signal_handlers_disconnect_by_func (priv->custom_title, check_headerbar_visbility, bar);
       priv->custom_title = NULL;
       gtk_widget_unparent (custom);
     }
@@ -1347,16 +1445,23 @@ gtk_header_bar_set_custom_title (GtkHead
       gtk_widget_set_parent (priv->custom_title, GTK_WIDGET (bar));
       gtk_widget_set_valign (priv->custom_title, GTK_ALIGN_CENTER);
 
+      g_signal_connect_swapped (priv->custom_title, "notify::visible", G_CALLBACK (check_headerbar_visbility), bar);
+
       if (priv->label_box != NULL)
         {
           GtkWidget *label_box = priv->label_box;
 
+          g_signal_handlers_disconnect_by_func (priv->title_label, check_headerbar_visbility, bar);
+          g_signal_handlers_disconnect_by_func (priv->subtitle_label, check_headerbar_visbility, bar);
+
           priv->label_box = NULL;
           priv->title_label = NULL;
           priv->subtitle_label = NULL;
+
           gtk_widget_unparent (label_box);
         }
 
+      check_headerbar_visbility (bar);
     }
   else
     {
@@ -1546,6 +1651,7 @@ notify_child_cb (GObject      *child,
                  GtkHeaderBar *bar)
 {
   _gtk_header_bar_update_separator_visibility (bar);
+  check_headerbar_visbility (bar);
 }
 
 static void
@@ -1573,6 +1679,7 @@ gtk_header_bar_pack (GtkHeaderBar *bar,
   gtk_widget_thaw_child_notify (widget);
 
   _gtk_header_bar_update_separator_visibility (bar);
+  check_headerbar_visbility (bar);
 }
 
 static void
@@ -1625,6 +1732,7 @@ gtk_header_bar_remove (GtkContainer *con
       g_free (child);
       gtk_widget_queue_resize (GTK_WIDGET (container));
       _gtk_header_bar_update_separator_visibility (bar);
+      check_headerbar_visbility (bar);
     }
 }
 
@@ -1808,6 +1916,22 @@ gtk_header_bar_realize (GtkWidget *widge
 
   GTK_WIDGET_CLASS (gtk_header_bar_parent_class)->realize (widget);
 
+#ifdef GDK_WINDOWING_X11
+  GtkHeaderBar *bar;
+  GtkHeaderBarPrivate *priv;
+  GdkScreen *screen;
+
+  bar = GTK_HEADER_BAR (widget);
+  priv = gtk_header_bar_get_instance_private (bar);
+  screen = gtk_widget_get_screen (widget);
+
+  if (GDK_IS_X11_SCREEN (screen))
+    {
+      GdkAtom unity_atom = gdk_atom_intern_static_string ("_UNITY_SHELL");
+      priv->unity_environment = gdk_x11_screen_supports_net_wm_hint (screen, unity_atom);
+    }
+#endif
+
   settings = gtk_widget_get_settings (widget);
   g_signal_connect_swapped (settings, "notify::gtk-shell-shows-app-menu",
                             G_CALLBACK (_gtk_header_bar_update_window_buttons), widget);
@@ -1856,6 +1980,8 @@ gtk_header_bar_hierarchy_changed (GtkWid
   if (toplevel)
     g_signal_connect_after (toplevel, "window-state-event",
                             G_CALLBACK (window_state_changed), widget);
+
+  check_title_visibility (GTK_HEADER_BAR (widget));
 }
 
 static void