overlay: add initial version of gtkoverlay

12 files changed, 1383 insertions, 0 deletions

diff --git a/demos/gtk-demo/Makefile.am b/demos/gtk-demo/Makefile.am
index 46b805a0bf..e4c45538df 100644
--- a/demos/gtk-demo/Makefile.am
+++ b/demos/gtk-demo/Makefile.am
@@ -30,6 +30,7 @@ demos =						\
 	menus.c					\
 	offscreen_window.c			\
 	offscreen_window2.c			\
+	overlay.c				\
 	panes.c					\
 	pickers.c				\
 	pixbufs.c				\
diff --git a/demos/gtk-demo/overlay.c b/demos/gtk-demo/overlay.c
new file mode 100644
index 0000000000..cbddd93cf6
--- /dev/null
+++ b/demos/gtk-demo/overlay.c
@@ -0,0 +1,181 @@
+/* Overlay
+ *
+ * Stack widgets in static positions over a main widget
+ */
+
+#include <gtk/gtk.h>
+
+GtkWidget *
+do_overlay (GtkWidget *do_widget)
+{
+  static GtkWidget *window = NULL;
+
+  if (!window)
+    {
+      GtkWidget *view;
+      GtkWidget *sw;
+      GtkWidget *overlay;
+      GtkWidget *entry;
+      GtkWidget *label;
+
+      window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+      gtk_window_set_screen (GTK_WINDOW (window),
+                             gtk_widget_get_screen (do_widget));
+      gtk_window_set_default_size (GTK_WINDOW (window),
+                                   450, 450);
+      
+      g_signal_connect (window, "destroy",
+                        G_CALLBACK (gtk_widget_destroyed), &window);
+
+      gtk_window_set_title (GTK_WINDOW (window), "Overlay");
+      gtk_container_set_border_width (GTK_CONTAINER (window), 0);
+
+      view = gtk_text_view_new ();
+
+      sw = gtk_scrolled_window_new (NULL, NULL);
+      gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (sw),
+                                      GTK_POLICY_AUTOMATIC,
+                                      GTK_POLICY_AUTOMATIC);
+      gtk_container_add (GTK_CONTAINER (sw), view);
+
+      overlay = gtk_overlay_new ();
+      gtk_container_add (GTK_CONTAINER (overlay), sw);
+      gtk_container_add (GTK_CONTAINER (window), overlay);
+
+      entry = gtk_entry_new ();
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+      gtk_widget_set_halign (entry, GTK_ALIGN_END);
+      gtk_widget_set_valign (entry, GTK_ALIGN_END);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_END);
+      gtk_widget_set_valign (label, GTK_ALIGN_END);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_START);
+      gtk_widget_set_valign (entry, GTK_ALIGN_END);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_START);
+      gtk_widget_set_valign (label, GTK_ALIGN_END);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_END);
+      gtk_widget_set_valign (entry, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_END);
+      gtk_widget_set_valign (label, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_START);
+      gtk_widget_set_valign (entry, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_START);
+      gtk_widget_set_valign (label, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_END);
+      gtk_widget_set_valign (entry, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_END);
+      gtk_widget_set_valign (label, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_START);
+      gtk_widget_set_valign (entry, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_START);
+      gtk_widget_set_valign (label, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (entry, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (label, GTK_ALIGN_START);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 20);
+      gtk_widget_set_margin_right (label, 20);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (entry, GTK_ALIGN_END);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (label, GTK_ALIGN_END);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+      gtk_widget_set_margin_left (label, 10);
+      gtk_widget_set_margin_right (label, 10);
+      gtk_widget_set_margin_top (label, 5);
+      gtk_widget_set_margin_bottom (label, 5);
+
+      entry = gtk_entry_new ();
+      gtk_widget_set_halign (entry, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (entry, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
+
+      label = gtk_label_new ("Hello world");
+      gtk_widget_set_halign (label, GTK_ALIGN_CENTER);
+      gtk_widget_set_valign (label, GTK_ALIGN_CENTER);
+      gtk_overlay_add_overlay (GTK_OVERLAY (overlay), label);
+
+      gtk_widget_show_all (overlay);
+    }
+
+  if (!gtk_widget_get_visible (window))
+    {
+      gtk_widget_show (window);
+    }
+  else
+    {
+      gtk_widget_destroy (window);
+      window = NULL;
+    }
+
+  return window;
+}
diff --git a/docs/reference/gtk/gtk-docs.sgml b/docs/reference/gtk/gtk-docs.sgml
index 0f80b241e4..98e0706bbc 100644
--- a/docs/reference/gtk/gtk-docs.sgml
+++ b/docs/reference/gtk/gtk-docs.sgml
@@ -242,6 +242,7 @@
       <xi:include href="xml/gtknotebook.xml" />
       <xi:include href="xml/gtktable.xml" />
       <xi:include href="xml/gtkexpander.xml" />
+      <xi:include href="xml/gtkoverlay.xml" />
       <xi:include href="xml/gtkorientable.xml" />
     </chapter>
 
diff --git a/docs/reference/gtk/gtk3-sections.txt b/docs/reference/gtk/gtk3-sections.txt
index 72c1a6f2aa..f0654c3c16 100644
--- a/docs/reference/gtk/gtk3-sections.txt
+++ b/docs/reference/gtk/gtk3-sections.txt
@@ -7079,3 +7079,29 @@ GTK_LOCK_BUTTON_GET_CLASS
 gtk_lock_button_get_type
 GtkLockButtonPrivate
 </SECTION>
+
+<SECTION>
+<FILE>gtkoverlay</FILE>
+<TITLE>GtkOverlay</TITLE>
+GtkOverlay
+
+gtk_overlay_new
+gtk_overlay_set_relative_widget
+gtk_overlay_get_relative_widget
+gtk_overlay_add
+gtk_overlay_set_offset
+gtk_overlay_get_offset
+
+<SUBSECTION Standard>
+GTK_TYPE_OVERLAY
+GTK_OVERLAY
+GTK_OVERLAY_CLASS
+GTK_IS_OVERLAY
+GTK_IS_OVERLAY_CLASS
+GTK_OVERLAY_GET_CLASS
+GtkOverlayClass
+
+<SUBSECTION Private>
+gtk_overlay_get_type
+GtkOverlayPrivate
+</SECTION>
diff --git a/docs/reference/gtk/gtk3.types b/docs/reference/gtk/gtk3.types
index 2b9cd79a43..d0190b7057 100644
--- a/docs/reference/gtk/gtk3.types
+++ b/docs/reference/gtk/gtk3.types
@@ -105,6 +105,7 @@ gtk_notebook_get_type
 gtk_numerable_icon_get_type
 gtk_offscreen_window_get_type
 gtk_orientable_get_type
+gtk_overlay_get_type
 gtk_page_setup_get_type
 gtk_page_setup_unix_dialog_get_type
 gtk_paned_get_type
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 493a80d2d6..70a35f4fbb 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -256,6 +256,7 @@ gtk_public_h_sources = 		\
 	gtknumerableicon.h	\
 	gtkoffscreenwindow.h	\
 	gtkorientable.h		\
+	gtkoverlay.h		\
 	gtkpagesetup.h		\
 	gtkpaned.h		\
 	gtkpapersize.h		\
@@ -592,6 +593,7 @@ gtk_base_c_sources = 		\
 	gtknumerableicon.c	\
 	gtkoffscreenwindow.c	\
 	gtkorientable.c		\
+	gtkoverlay.c		\
 	gtkpagesetup.c		\
 	gtkpaned.c		\
 	gtkpango.c		\
diff --git a/gtk/gtk.h b/gtk/gtk.h
index 6d6b416c09..c6441110da 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -141,6 +141,7 @@
 #include <gtk/gtknumerableicon.h>
 #include <gtk/gtkoffscreenwindow.h>
 #include <gtk/gtkorientable.h>
+#include <gtk/gtkoverlay.h>
 #include <gtk/gtkpagesetup.h>
 #include <gtk/gtkpapersize.h>
 #include <gtk/gtkpaned.h>
diff --git a/gtk/gtk.symbols b/gtk/gtk.symbols
index 3063cc7ecb..cde5ce5c5a 100644
--- a/gtk/gtk.symbols
+++ b/gtk/gtk.symbols
@@ -1625,6 +1625,9 @@ gtk_orientable_get_orientation
 gtk_orientable_get_type
 gtk_orientable_set_orientation
 gtk_orientation_get_type
+gtk_overlay_add_overlay
+gtk_overlay_get_type
+gtk_overlay_new
 gtk_pack_direction_get_type
 gtk_pack_type_get_type
 gtk_page_orientation_get_type
diff --git a/gtk/gtkoverlay.c b/gtk/gtkoverlay.c
new file mode 100644
index 0000000000..40125babaa
--- /dev/null
+++ b/gtk/gtkoverlay.c
@@ -0,0 +1,635 @@
+/*
+ * gtkoverlay.c
+ * This file is part of gtk
+ *
+ * Copyright (C) 2011 - Ignacio Casal Quinteiro, Mike Krüger
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include "gtkoverlay.h"
+#include "gtkbuildable.h"
+#include "gtkscrolledwindow.h"
+#include "gtkmainprivate.h"
+#include "gtkmarshalers.h"
+
+#include "gtkprivate.h"
+#include "gtkintl.h"
+
+/**
+ * SECTION:gtkoverlay
+ * @short_description: A container which overlays widgets on top of each other
+ * @title: GtkOverlay
+ *
+ * GtkOverlay is a container which contains a single main child, on top
+ * of which it can place <firstterm>overlay</firstterm> widgets. The
+ * position of each overlay widget is determined by its #GtkWidget::halign
+ * and #GtkWidget::valign properties. E.g. a widget with both alignments
+ * set to %GTK_ALIGN_START will be placed at the top left corner of the
+ * main widget, whereas an overlay with halign set to %GTK_ALIGN_CENTER
+ * and valign set to %GTK_ALIGN_END will be placed a the bottom edge of
+ * the main widget, horizontally centered. The position can be adjusted
+ * by setting the margin properties of the child to non-zero values.
+ *
+ * More complicated placement of overlays is possible by connecting
+ * to the #GtkOverlay::get-child-position signal.
+ *
+ * <refsect2 id="GtkOverlay-BUILDER-UI">
+ * <title>GtkOverlay as GtkBuildable</title>
+ * <para>
+ * The GtkOverlay implementation of the GtkBuildable interface
+ * supports placing a child as an overlay by specifying "overlay" as
+ * the "type" attribute of a <tag class="starttag">child</tag> element.
+ * </para>
+ * </refsect2>
+ */
+
+struct _GtkOverlayPrivate
+{
+  GSList *children;
+};
+
+typedef struct _GtkOverlayChild GtkOverlayChild;
+
+struct _GtkOverlayChild
+{
+  GtkWidget *widget;
+  GdkWindow *window;
+};
+
+enum {
+  GET_CHILD_POSITION,
+  LAST_SIGNAL
+};
+
+static guint signals[LAST_SIGNAL] = { 0 };
+
+static void gtk_overlay_buildable_init (GtkBuildableIface *iface);
+
+G_DEFINE_TYPE_WITH_CODE (GtkOverlay, gtk_overlay, GTK_TYPE_BIN,
+                         G_IMPLEMENT_INTERFACE (GTK_TYPE_BUILDABLE,
+                                                gtk_overlay_buildable_init))
+
+static GdkWindow *
+gtk_overlay_create_child_window (GtkOverlay *overlay,
+                                 GtkWidget  *child)
+{
+  GtkWidget *widget = GTK_WIDGET (overlay);
+  GtkAllocation allocation;
+  GdkWindow *window;
+  GdkWindowAttr attributes;
+  gint attributes_mask;
+
+  gtk_widget_get_allocation (child, &allocation);
+
+  attributes.window_type = GDK_WINDOW_CHILD;
+  attributes.wclass = GDK_INPUT_OUTPUT;
+  attributes.width = allocation.width;
+  attributes.height = allocation.height;
+  attributes.x = allocation.x;
+  attributes.y = allocation.y;
+  attributes_mask = GDK_WA_X | GDK_WA_Y;
+  attributes.event_mask = gtk_widget_get_events (widget) | GDK_EXPOSURE_MASK;
+
+  window = gdk_window_new (gtk_widget_get_window (widget),
+                           &attributes, attributes_mask);
+  gdk_window_set_user_data (window, overlay);
+  gtk_style_context_set_background (gtk_widget_get_style_context (widget), window);
+
+  gtk_widget_set_parent_window (child, window);
+
+  return window;
+}
+
+static void
+gtk_overlay_child_allocate (GtkOverlayChild *child,
+                            GtkAllocation   *allocation)
+{
+  gint left, right, top, bottom;
+  GtkAllocation child_allocation;
+
+  /* put the margins outside the window; also arrange things
+   * so that the adjusted child allocation still ends up at 0, 0
+   */
+  left = gtk_widget_get_margin_left (child->widget);
+  right = gtk_widget_get_margin_right (child->widget);
+  top = gtk_widget_get_margin_top (child->widget);
+  bottom = gtk_widget_get_margin_bottom (child->widget);
+
+  child_allocation.x = - left;
+  child_allocation.y = - top;
+  child_allocation.width = allocation->width;
+  child_allocation.height = allocation->height;
+
+  allocation->x += left;
+  allocation->y += top;
+  allocation->width -= left + right;
+  allocation->height -= top + bottom;
+
+  if (child->window)
+    gdk_window_move_resize (child->window,
+                            allocation->x, allocation->y,
+                            allocation->width, allocation->height);
+
+  gtk_widget_size_allocate (child->widget, &child_allocation);
+}
+
+static void
+gtk_overlay_get_preferred_width (GtkWidget *widget,
+                                 gint      *minimum,
+                                 gint      *natural)
+{
+  GtkBin *bin = GTK_BIN (widget);
+  GtkWidget *child;
+
+  if (minimum)
+    *minimum = 0;
+
+  if (natural)
+    *natural = 0;
+
+  child = gtk_bin_get_child (bin);
+  if (child && gtk_widget_get_visible (child))
+    gtk_widget_get_preferred_width (child, minimum, natural);
+}
+
+static void
+gtk_overlay_get_preferred_height (GtkWidget *widget,
+                                  gint      *minimum,
+                                  gint      *natural)
+{
+  GtkBin *bin = GTK_BIN (widget);
+  GtkWidget *child;
+
+  if (minimum)
+    *minimum = 0;
+
+  if (natural)
+    *natural = 0;
+
+  child = gtk_bin_get_child (bin);
+  if (child && gtk_widget_get_visible (child))
+    gtk_widget_get_preferred_height (child, minimum, natural);
+}
+
+static void
+gtk_overlay_size_allocate (GtkWidget     *widget,
+                           GtkAllocation *allocation)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GSList *children;
+  GtkWidget *main_widget;
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->size_allocate (widget, allocation);
+
+  main_widget = gtk_bin_get_child (GTK_BIN (overlay));
+  if (!main_widget || !gtk_widget_get_visible (main_widget))
+    return;
+
+  gtk_widget_size_allocate (main_widget, allocation);
+
+  for (children = priv->children; children; children = children->next)
+    {
+      GtkOverlayChild *child;
+      GtkAllocation alloc;
+      gboolean result;
+
+      child = children->data;
+
+      if (gtk_widget_get_mapped (GTK_WIDGET (overlay)))
+        {
+          if (gtk_widget_get_visible (child->widget))
+            gdk_window_show (child->window);
+          else if (gdk_window_is_visible (child->window))
+            gdk_window_hide (child->window);
+        }
+
+      if (!gtk_widget_get_visible (child->widget))
+        continue;
+
+      g_signal_emit (overlay, signals[GET_CHILD_POSITION],
+                     0, child->widget, &alloc, &result);
+
+      alloc.x += allocation->x;
+      alloc.y += allocation->y;
+
+      gtk_overlay_child_allocate (child, &alloc);
+    }
+}
+
+static GtkAlign
+effective_align (GtkAlign         align,
+                 GtkTextDirection direction)
+{
+  switch (align)
+    {
+    case GTK_ALIGN_START:
+      return direction == GTK_TEXT_DIR_RTL ? GTK_ALIGN_END : GTK_ALIGN_START;
+    case GTK_ALIGN_END:
+      return direction == GTK_TEXT_DIR_RTL ? GTK_ALIGN_START : GTK_ALIGN_END;
+    default:
+      return align;
+    }
+}
+
+static gboolean
+gtk_overlay_get_child_position (GtkOverlay    *overlay,
+                                GtkWidget     *widget,
+                                GtkAllocation *alloc)
+{
+  GtkWidget *main_widget;
+  GtkAllocation main_alloc;
+  GtkRequisition req;
+  GtkAlign halign;
+  GtkTextDirection direction;
+
+  main_widget = gtk_bin_get_child (GTK_BIN (overlay));
+
+  /* special-case scrolled windows */
+  if (GTK_IS_SCROLLED_WINDOW (main_widget))
+    {
+      GtkWidget *grandchild;
+      gint x, y;
+
+      grandchild = gtk_bin_get_child (GTK_BIN (main_widget));
+      gtk_widget_translate_coordinates (grandchild, main_widget, 0, 0, &x, &y);
+
+      main_alloc.x = x;
+      main_alloc.y = y;
+      main_alloc.width = gtk_widget_get_allocated_width (grandchild);
+      main_alloc.height = gtk_widget_get_allocated_height (grandchild);
+    }
+  else
+    {
+      main_alloc.x = 0;
+      main_alloc.y = 0;
+      main_alloc.width = gtk_widget_get_allocated_width (main_widget);
+      main_alloc.height = gtk_widget_get_allocated_height (main_widget);
+    }
+
+  gtk_widget_get_preferred_size (widget, NULL, &req);
+
+  alloc->x = main_alloc.x;
+  alloc->width = MIN (main_alloc.width, req.width);
+
+  direction = gtk_widget_get_direction (widget);
+
+  halign = gtk_widget_get_halign (widget);
+  switch (effective_align (halign, direction))
+    {
+    case GTK_ALIGN_START:
+      /* nothing to do */
+      break;
+    case GTK_ALIGN_FILL:
+      alloc->width = main_alloc.width;
+      break;
+    case GTK_ALIGN_CENTER:
+      alloc->x += main_alloc.width / 2 - req.width / 2;
+      break;
+    case GTK_ALIGN_END:
+      alloc->x += main_alloc.width - req.width;
+      break;
+    }
+
+  alloc->y = main_alloc.y;
+  alloc->height = MIN (main_alloc.height, req.height);
+
+  switch (gtk_widget_get_valign (widget))
+    {
+    case GTK_ALIGN_START:
+      /* nothing to do */
+      break;
+    case GTK_ALIGN_FILL:
+      alloc->height = main_alloc.height;
+      break;
+    case GTK_ALIGN_CENTER:
+      alloc->y += main_alloc.height / 2 - req.height / 2;
+      break;
+    case GTK_ALIGN_END:
+      alloc->y += main_alloc.height - req.height;
+      break;
+    }
+
+  return TRUE;
+}
+
+static void
+gtk_overlay_realize (GtkWidget *widget)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->realize (widget);
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      if (child->window == NULL)
+        child->window = gtk_overlay_create_child_window (overlay, child->widget);
+    }
+}
+
+static void
+gtk_overlay_unrealize (GtkWidget *widget)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      gtk_widget_set_parent_window (child->widget, NULL);
+      gdk_window_set_user_data (child->window, NULL);
+      gdk_window_destroy (child->window);
+      child->window = NULL;
+    }
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->unrealize (widget);
+}
+
+static void
+gtk_overlay_map (GtkWidget *widget)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->map (widget);
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      if (child->window != NULL &&
+          gtk_widget_get_visible (child->widget) &&
+          gtk_widget_get_child_visible (child->widget))
+        gdk_window_show (child->window);
+    }
+}
+
+static void
+gtk_overlay_unmap (GtkWidget *widget)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      if (child->window != NULL &&
+          gdk_window_is_visible (child->window))
+        gdk_window_hide (child->window);
+    }
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->unmap (widget);
+}
+
+static gboolean
+gtk_overlay_draw (GtkWidget *widget,
+                  cairo_t   *cr)
+{
+  GtkOverlay *overlay = GTK_OVERLAY (widget);
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      if (gtk_cairo_should_draw_window (cr, child->window))
+        {
+          cairo_save (cr);
+          gtk_cairo_transform_to_window (cr, widget, child->window);
+          gtk_render_background (gtk_widget_get_style_context (widget),
+                                 cr,
+                                 0, 0,
+                                 gdk_window_get_width (child->window),
+                                 gdk_window_get_height (child->window));
+          cairo_restore (cr);
+        }
+    }
+
+  GTK_WIDGET_CLASS (gtk_overlay_parent_class)->draw (widget, cr);
+
+  return FALSE;
+}
+
+static void
+gtk_overlay_remove (GtkContainer *container,
+                    GtkWidget    *widget)
+{
+  GtkOverlayPrivate *priv = GTK_OVERLAY (container)->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+
+  for (children = priv->children; children; children = children->next)
+    {
+      child = children->data;
+
+      if (child->widget == widget)
+        {
+          if (child->window != NULL)
+            {
+              gdk_window_set_user_data (child->window, NULL);
+              gdk_window_destroy (child->window);
+            }
+
+          gtk_widget_unparent (widget);
+
+          priv->children = g_slist_delete_link (priv->children, children);
+          g_slice_free (GtkOverlayChild, child);
+
+          return;
+        }
+    }
+
+  GTK_CONTAINER_CLASS (gtk_overlay_parent_class)->remove (container, widget);
+}
+
+static void
+gtk_overlay_forall (GtkContainer *overlay,
+                    gboolean      include_internals,
+                    GtkCallback   callback,
+                    gpointer      callback_data)
+{
+  GtkOverlayPrivate *priv = GTK_OVERLAY (overlay)->priv;
+  GtkOverlayChild *child;
+  GSList *children;
+  GtkWidget *main_widget;
+
+  main_widget = gtk_bin_get_child (GTK_BIN (overlay));
+  if (main_widget)
+    (* callback) (main_widget, callback_data);
+
+  children = priv->children;
+  while (children)
+    {
+      child = children->data;
+      children = children->next;
+
+      (* callback) (child->widget, callback_data);
+    }
+}
+
+static void
+gtk_overlay_class_init (GtkOverlayClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+  GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
+  GtkContainerClass *container_class = GTK_CONTAINER_CLASS (klass);
+
+  widget_class->get_preferred_width = gtk_overlay_get_preferred_width;
+  widget_class->get_preferred_height = gtk_overlay_get_preferred_height;
+  widget_class->size_allocate = gtk_overlay_size_allocate;
+  widget_class->realize = gtk_overlay_realize;
+  widget_class->unrealize = gtk_overlay_unrealize;
+  widget_class->map = gtk_overlay_map;
+  widget_class->unmap = gtk_overlay_unmap;
+  widget_class->draw = gtk_overlay_draw;
+
+  container_class->remove = gtk_overlay_remove;
+  container_class->forall = gtk_overlay_forall;
+
+  klass->get_child_position = gtk_overlay_get_child_position;
+
+  /**
+   * GtkOverlay::get-child-position:
+   * @overlay: the #GtkOverlay
+   * @widget: the child widget to position
+   * @allocation: (out): return location for the allocation
+   *
+   * The ::get-child-position signal is emitted to determine
+   * the position and size of any overlay child widgets. A
+   * handler for this signal should fill @allocation with
+   * the desired position and size for @widget, relative to
+   * the 'main' child of @overlay.
+   *
+   * The default handler for this signal uses the @widget's
+   * halign and valign properties to determine the position
+   * and gives the widget its natural size (except that an
+   * alignment of %GTK_ALIGN_FILL will cause the overlay to
+   * be full-width/height). If the main child is a
+   * #GtkScrolledWindow, the overlays are placed relative
+   * to its contents.
+   *
+   * Return: %TRUE if the @allocation has been filled
+   */
+  signals[GET_CHILD_POSITION] =
+    g_signal_new (I_("get-child-position"),
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (GtkOverlayClass, get_child_position),
+                  _gtk_boolean_handled_accumulator, NULL,
+                  _gtk_marshal_BOOLEAN__OBJECT_BOXED,
+                  G_TYPE_BOOLEAN, 2,
+                  GTK_TYPE_WIDGET,
+                  GDK_TYPE_RECTANGLE | G_SIGNAL_TYPE_STATIC_SCOPE);
+
+  g_type_class_add_private (object_class, sizeof (GtkOverlayPrivate));
+}
+
+static void
+gtk_overlay_init (GtkOverlay *overlay)
+{
+  overlay->priv = G_TYPE_INSTANCE_GET_PRIVATE (overlay, GTK_TYPE_OVERLAY, GtkOverlayPrivate);
+
+  gtk_widget_set_has_window (GTK_WIDGET (overlay), FALSE);
+}
+
+static void
+gtk_overlay_buildable_add_child (GtkBuildable *buildable,
+                                 GtkBuilder   *builder,
+                                 GObject      *child,
+                                 const gchar  *type)
+{
+  if (type && strcmp (type, "overlay") == 0)
+    gtk_overlay_add_overlay (GTK_OVERLAY (buildable), GTK_WIDGET (child));
+  else if (!type)
+    gtk_container_add (GTK_CONTAINER (buildable), GTK_WIDGET (child));
+  else
+    GTK_BUILDER_WARN_INVALID_CHILD_TYPE (buildable, type);
+}
+
+static void
+gtk_overlay_buildable_init (GtkBuildableIface *iface)
+{
+  iface->add_child = gtk_overlay_buildable_add_child;
+}
+
+/**
+ * gtk_overlay_new:
+ *
+ * Creates a new #GtkOverlay.
+ *
+ * Returns: a new #GtkOverlay object.
+ *
+ * Since: 3.2
+ */
+GtkWidget *
+gtk_overlay_new (void)
+{
+  return g_object_new (GTK_TYPE_OVERLAY, NULL);
+}
+
+/**
+ * gtk_overlay_add_overlay:
+ * @overlay: a #GtkOverlay
+ * @widget: a #GtkWidget to be added to the container
+ *
+ * Adds @widget to @overlay.
+ *
+ * The widget will be stacked on top of the main widget
+ * added with gtk_container_add().
+ *
+ * The position at which @widget is placed is determined
+ * from its #GtkWidget::halign and #GtkWidget::valign properties.
+ *
+ * Since: 3.2
+ */
+void
+gtk_overlay_add_overlay (GtkOverlay *overlay,
+                         GtkWidget  *widget)
+{
+  GtkOverlayPrivate *priv = overlay->priv;
+  GtkOverlayChild *child;
+
+  g_return_if_fail (GTK_IS_OVERLAY (overlay));
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+
+  child = g_slice_new0 (GtkOverlayChild);
+  child->widget = widget;
+
+  gtk_widget_set_parent (widget, GTK_WIDGET (overlay));
+
+  priv->children = g_slist_append (priv->children, child);
+
+  if (gtk_widget_get_realized (GTK_WIDGET (overlay)))
+    child->window = gtk_overlay_create_child_window (overlay, widget);
+}
diff --git a/gtk/gtkoverlay.h b/gtk/gtkoverlay.h
new file mode 100644
index 0000000000..baa0e57bcf
--- /dev/null
+++ b/gtk/gtkoverlay.h
@@ -0,0 +1,79 @@
+/*
+ * gtkoverlay.h
+ * This file is part of gtk
+ *
+ * Copyright (C) 2011 - Ignacio Casal Quinteiro
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#ifndef __GTK_OVERLAY_H__
+#define __GTK_OVERLAY_H__
+
+#include <gtk/gtkbin.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_OVERLAY             (gtk_overlay_get_type ())
+#define GTK_OVERLAY(obj)             (G_TYPE_CHECK_INSTANCE_CAST ((obj), GTK_TYPE_OVERLAY, GtkOverlay))
+#define GTK_OVERLAY_CLASS(klass)     (G_TYPE_CHECK_CLASS_CAST ((klass), GTK_TYPE_OVERLAY, GtkOverlayClass))
+#define GTK_IS_OVERLAY(obj)          (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GTK_TYPE_OVERLAY))
+#define GTK_IS_OVERLAY_CLASS(klass)  (G_TYPE_CHECK_CLASS_TYPE ((klass), GTK_TYPE_OVERLAY))
+#define GTK_OVERLAY_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS ((obj), GTK_TYPE_OVERLAY, GtkOverlayClass))
+
+typedef struct _GtkOverlay         GtkOverlay;
+typedef struct _GtkOverlayClass    GtkOverlayClass;
+typedef struct _GtkOverlayPrivate  GtkOverlayPrivate;
+
+struct _GtkOverlay
+{
+  GtkBin parent;
+
+  GtkOverlayPrivate *priv;
+};
+
+struct _GtkOverlayClass
+{
+  GtkBinClass parent_class;
+
+  gboolean (*get_child_position) (GtkOverlay    *overlay,
+                                  GtkWidget     *widget,
+                                  GtkAllocation *allocation);
+
+  /* Padding for future expansion */
+  void (*_gtk_reserved1) (void);
+  void (*_gtk_reserved2) (void);
+  void (*_gtk_reserved3) (void);
+  void (*_gtk_reserved4) (void);
+  void (*_gtk_reserved5) (void);
+  void (*_gtk_reserved6) (void);
+  void (*_gtk_reserved7) (void);
+  void (*_gtk_reserved8) (void);
+};
+
+GType      gtk_overlay_get_type    (void) G_GNUC_CONST;
+
+GtkWidget *gtk_overlay_new         (void);
+void       gtk_overlay_add_overlay (GtkOverlay *overlay,
+                                    GtkWidget  *widget);
+
+G_END_DECLS
+
+#endif /* __GTK_OVERLAY_H__ */
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 3cbf6fab85..74d22649b2 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -71,6 +71,7 @@ noinst_PROGRAMS =  $(TEST_PROGS)	\
 	testoffscreen			\
 	testoffscreenwindow		\
 	testorientable			\
+	testoverlay			\
 	testprint			\
 	testrecentchooser 		\
 	testrecentchoosermenu		\
@@ -177,6 +178,7 @@ testoffscreenwindow_DEPENDENCIES = $(TEST_DEPS)
 testappchooser_DEPENDENCIES = $(TEST_DEPS)
 testappchooserbutton_DEPENDENCIES = $(TEST_DEPS)
 testorientable_DEPENDENCIES = $(TEST_DEPS)
+testoverlay_DEPENDENCIES = $(TEST_DEPS)
 testprint_DEPENDENCIES = $(TEST_DEPS)
 testrecentchooser_DEPENDENCIES = $(TEST_DEPS)
 testrecentchoosermenu_DEPENDENCIES = $(TEST_DEPS)
@@ -266,6 +268,7 @@ testoffscreenwindow_LDADD = $(LDADDS)
 testappchooser_LDADD = $(LDADDS)
 testappchooserbutton_LDADD = $(LDADDS)
 testorientable_LDADD = $(LDADDS)
+testoverlay_LDADD = $(LDADDS)
 testprint_LDADD = $(LDADDS)
 testrecentchooser_LDADD = $(LDADDS)
 testrecentchoosermenu_LDADD = $(LDADDS)
@@ -441,6 +444,9 @@ testoffscreen_SOURCES = 	\
 testoffscreenwindow_SOURCES =	\
 	testoffscreenwindow.c
 
+testoverlay_SOURCES =	\
+	testoverlay.c
+
 testappchooser_SOURCES = \
 	testappchooser.c
 
diff --git a/tests/testoverlay.c b/tests/testoverlay.c
new file mode 100644
index 0000000000..d59032c33a
--- /dev/null
+++ b/tests/testoverlay.c
@@ -0,0 +1,447 @@
+#include <string.h>
+#include <gtk/gtk.h>
+
+/* test that margins and non-zero allocation x/y
+ * of the main widget are handled correctly
+ */
+static GtkWidget *
+test_nonzerox (void)
+{
+  GtkWidget *win;
+  GtkWidget *grid;
+  GtkWidget *overlay;
+  GtkWidget *text;
+  GtkWidget *child;
+  GdkRGBA color;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Non-zero X");
+
+  grid = gtk_grid_new ();
+  g_object_set (grid, "margin", 5, NULL);
+  gtk_container_add (GTK_CONTAINER (win), grid);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Above"), 1, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Below"), 1, 2, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Left"), 0, 1, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Right"), 2, 1, 1, 1);
+
+  overlay = gtk_overlay_new ();
+  gdk_rgba_parse (&color, "red");
+  gtk_widget_override_background_color (overlay, 0, &color);
+  gtk_grid_attach (GTK_GRID (grid), overlay, 1, 1, 1, 1);
+
+  text = gtk_text_view_new ();
+  gtk_widget_set_size_request (text, 200, 200);
+  gtk_widget_set_hexpand (text, TRUE);
+  gtk_widget_set_vexpand (text, TRUE);
+  gtk_container_add (GTK_CONTAINER (overlay), text);
+
+  child = gtk_label_new ("I'm the overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_START);
+  gtk_widget_set_valign (child, GTK_ALIGN_START);
+  g_object_set (child, "margin", 3, NULL);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+
+  child = gtk_label_new ("No, I'm the overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_END);
+  gtk_widget_set_valign (child, GTK_ALIGN_END);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 3, NULL);
+
+  return win;
+}
+
+static gboolean
+get_child_position (GtkOverlay    *overlay,
+                    GtkWidget     *widget,
+                    GtkAllocation *alloc,
+                    GtkWidget     *relative)
+{
+  GtkRequisition req;
+  GtkWidget *child;
+  GtkAllocation main_alloc;
+  gint x, y;
+
+  child = gtk_bin_get_child (GTK_BIN (overlay));
+
+  gtk_widget_translate_coordinates (relative, child, 0, 0, &x, &y);
+  main_alloc.x = x;
+  main_alloc.y = y;
+  main_alloc.width = gtk_widget_get_allocated_width (relative);
+  main_alloc.height = gtk_widget_get_allocated_height (relative);
+
+  gtk_widget_get_preferred_size (widget, NULL, &req);
+
+  alloc->x = main_alloc.x;
+  alloc->width = MIN (main_alloc.width, req.width);
+  if (gtk_widget_get_halign (widget) == GTK_ALIGN_END)
+    alloc->x += main_alloc.width - req.width;
+
+  alloc->y = main_alloc.y;
+  alloc->height = MIN (main_alloc.height, req.height);
+  if (gtk_widget_get_valign (widget) == GTK_ALIGN_END)
+    alloc->y += main_alloc.height - req.height;
+
+  return TRUE;
+}
+
+/* test custom positioning */
+static GtkWidget *
+test_relative (void)
+{
+  GtkWidget *win;
+  GtkWidget *grid;
+  GtkWidget *overlay;
+  GtkWidget *text;
+  GtkWidget *child;
+  GdkRGBA color;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Custom positioning");
+
+  overlay = gtk_overlay_new ();
+  gdk_rgba_parse (&color, "yellow");
+  gtk_widget_override_background_color (overlay, 0, &color);
+  gtk_container_add (GTK_CONTAINER (win), overlay);
+
+  grid = gtk_grid_new ();
+  gtk_container_add (GTK_CONTAINER (overlay), grid);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Above"), 1, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Below"), 1, 2, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Left"), 0, 1, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), gtk_label_new ("Right"), 2, 1, 1, 1);
+
+  text = gtk_text_view_new ();
+  gtk_widget_set_size_request (text, 200, 200);
+  g_object_set (text, "margin", 5, NULL);
+  gtk_widget_set_hexpand (text, TRUE);
+  gtk_widget_set_vexpand (text, TRUE);
+  gtk_grid_attach (GTK_GRID (grid), text, 1, 1, 1, 1);
+  g_signal_connect (overlay, "get-child-position",
+                    G_CALLBACK (get_child_position), text);
+
+  child = gtk_label_new ("Top left overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_START);
+  gtk_widget_set_valign (child, GTK_ALIGN_START);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 1, NULL);
+
+  child = gtk_label_new ("Bottom right overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_END);
+  gtk_widget_set_valign (child, GTK_ALIGN_END);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 1, NULL);
+
+  return win;
+}
+
+/* test GTK_ALIGN_FILL handling */
+static GtkWidget *
+test_fullwidth (void)
+{
+  GtkWidget *win;
+  GtkWidget *overlay;
+  GtkWidget *text;
+  GtkWidget *child;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Full-width");
+
+  overlay = gtk_overlay_new ();
+  gtk_container_add (GTK_CONTAINER (win), overlay);
+
+  text = gtk_text_view_new ();
+  gtk_widget_set_size_request (text, 200, 200);
+  gtk_widget_set_hexpand (text, TRUE);
+  gtk_widget_set_vexpand (text, TRUE);
+  gtk_container_add (GTK_CONTAINER (overlay), text);
+
+  child = gtk_label_new ("Fullwidth top overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_FILL);
+  gtk_widget_set_valign (child, GTK_ALIGN_START);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 4, NULL);
+
+  return win;
+}
+
+/* test that scrolling works as expected */
+static GtkWidget *
+test_scrolling (void)
+{
+  GtkWidget *win;
+  GtkWidget *overlay;
+  GtkWidget *sw;
+  GtkWidget *text;
+  GtkWidget *child;
+  GtkTextBuffer *buffer;
+  gchar *contents;
+  gsize len;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Scrolling");
+
+  overlay = gtk_overlay_new ();
+  gtk_container_add (GTK_CONTAINER (win), overlay);
+
+  sw = gtk_scrolled_window_new (NULL, NULL);
+  gtk_scrolled_window_set_min_content_width (GTK_SCROLLED_WINDOW (sw), 200);
+  gtk_scrolled_window_set_min_content_height (GTK_SCROLLED_WINDOW (sw), 200);
+  gtk_container_add (GTK_CONTAINER (overlay), sw);
+
+  text = gtk_text_view_new ();
+  buffer = gtk_text_buffer_new (NULL);
+  if (!g_file_get_contents ("testoverlay.c", &contents, &len, NULL))
+    {
+      contents = g_strdup ("Text should go here...");
+      len = strlen (contents);
+    }
+  gtk_text_buffer_set_text (buffer, contents, len);
+  g_free (contents);
+  gtk_text_view_set_buffer (GTK_TEXT_VIEW (text), buffer);
+
+  gtk_widget_set_hexpand (text, TRUE);
+  gtk_widget_set_vexpand (text, TRUE);
+  gtk_container_add (GTK_CONTAINER (sw), text);
+
+  child = gtk_label_new ("This should be visible");
+  gtk_widget_set_halign (child, GTK_ALIGN_CENTER);
+  gtk_widget_set_valign (child, GTK_ALIGN_END);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 4, NULL);
+
+  return win;
+}
+
+static const gchar *buffer =
+"<interface>"
+"  <object class='GtkWindow' id='window'>"
+"    <property name='title'>GtkBuilder support</property>"
+"    <child>"
+"      <object class='GtkOverlay' id='overlay'>"
+"        <child type='overlay'>"
+"          <object class='GtkLabel' id='overlay-child'>"
+"            <property name='label'>Witty remark goes here</property>"
+"            <property name='halign'>end</property>"
+"            <property name='valign'>end</property>"
+"            <property name='margin'>4</property>"
+"          </object>"
+"        </child>"
+"        <child>"
+"          <object class='GtkGrid' id='grid'>"
+"            <child>"
+"              <object class='GtkLabel' id='left'>"
+"                <property name='label'>Left</property>"
+"              </object>"
+"              <packing>"
+"                <property name='left_attach'>0</property>"
+"                <property name='top_attach'>0</property>"
+"              </packing>"
+"            </child>"
+"            <child>"
+"              <object class='GtkLabel' id='right'>"
+"                <property name='label'>Right</property>"
+"              </object>"
+"              <packing>"
+"                <property name='left_attach'>2</property>"
+"                <property name='top_attach'>0</property>"
+"              </packing>"
+"            </child>"
+"            <child>"
+"              <object class='GtkTextView' id='text'>"
+"                 <property name='width-request'>200</property>"
+"                 <property name='height-request'>200</property>"
+"                 <property name='hexpand'>True</property>"
+"                 <property name='vexpand'>True</property>"
+"              </object>"
+"              <packing>"
+"                <property name='left_attach'>1</property>"
+"                <property name='top_attach'>0</property>"
+"              </packing>"
+"            </child>"
+"          </object>"
+"        </child>"
+"      </object>"
+"    </child>"
+"  </object>"
+"</interface>";
+
+/* test that overlays can be constructed with GtkBuilder */
+static GtkWidget *
+test_builder (void)
+{
+  GtkBuilder *builder;
+  GtkWidget *win;
+  GError *error;
+
+  builder = gtk_builder_new ();
+
+  error = NULL;
+  if (!gtk_builder_add_from_string (builder, buffer, -1, &error))
+    {
+      g_warning ("%s", error->message);
+      g_error_free (error);
+      return NULL;
+    }
+
+  win = (GtkWidget *)gtk_builder_get_object (builder, "window");
+  g_object_ref (win);
+
+  g_object_unref (builder);
+
+  return win;
+}
+
+static void
+on_enter (GtkWidget *overlay, GdkEventCrossing *event, GtkWidget *child)
+{
+  if (event->window != gtk_widget_get_window (child))
+    return;
+
+  if (gtk_widget_get_halign (child) == GTK_ALIGN_START)
+    gtk_widget_set_halign (child, GTK_ALIGN_END);
+  else
+    gtk_widget_set_halign (child, GTK_ALIGN_START);
+
+  gtk_widget_queue_resize (overlay);
+}
+
+static GtkWidget *
+test_chase (void)
+{
+  GtkWidget *win;
+  GtkWidget *overlay;
+  GtkWidget *sw;
+  GtkWidget *text;
+  GtkWidget *child;
+  GtkTextBuffer *buffer;
+  gchar *contents;
+  gsize len;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Chase");
+
+  overlay = gtk_overlay_new ();
+  gtk_widget_set_events (overlay, GDK_ENTER_NOTIFY_MASK|GDK_LEAVE_NOTIFY_MASK);
+  gtk_container_add (GTK_CONTAINER (win), overlay);
+
+  sw = gtk_scrolled_window_new (NULL, NULL);
+  gtk_scrolled_window_set_min_content_width (GTK_SCROLLED_WINDOW (sw), 200);
+  gtk_scrolled_window_set_min_content_height (GTK_SCROLLED_WINDOW (sw), 200);
+  gtk_container_add (GTK_CONTAINER (overlay), sw);
+
+  text = gtk_text_view_new ();
+  buffer = gtk_text_buffer_new (NULL);
+  if (!g_file_get_contents ("testoverlay.c", &contents, &len, NULL))
+    {
+      contents = g_strdup ("Text should go here...");
+      len = strlen (contents);
+    }
+  gtk_text_buffer_set_text (buffer, contents, len);
+  g_free (contents);
+  gtk_text_view_set_buffer (GTK_TEXT_VIEW (text), buffer);
+
+  gtk_widget_set_hexpand (text, TRUE);
+  gtk_widget_set_vexpand (text, TRUE);
+  gtk_container_add (GTK_CONTAINER (sw), text);
+
+  child = gtk_label_new ("Try to enter");
+  gtk_widget_set_halign (child, GTK_ALIGN_START);
+  gtk_widget_set_valign (child, GTK_ALIGN_END);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  g_object_set (child, "margin", 4, NULL);
+
+  g_signal_connect (overlay, "enter-notify-event",
+                    G_CALLBACK (on_enter), child);
+  return win;
+}
+
+static GtkWidget *
+test_stacking (void)
+{
+  GtkWidget *win;
+  GtkWidget *overlay;
+  GtkWidget *main_child;
+  GtkWidget *label;
+  GtkWidget *child;
+  GtkWidget *grid;
+  GtkWidget *check1;
+  GtkWidget *check2;
+  GdkRGBA color;
+
+  win = gtk_window_new (GTK_WINDOW_TOPLEVEL);
+  gtk_window_set_title (GTK_WINDOW (win), "Stacking");
+
+  grid = gtk_grid_new ();
+  overlay = gtk_overlay_new ();
+  main_child = gtk_event_box_new ();
+  gdk_rgba_parse (&color, "green");
+  gtk_widget_override_background_color (main_child, 0, &color);
+  gtk_widget_set_hexpand (main_child, TRUE);
+  gtk_widget_set_vexpand (main_child, TRUE);
+  label = gtk_label_new ("Main child");
+  child = gtk_label_new ("Overlay");
+  gtk_widget_set_halign (child, GTK_ALIGN_END);
+  gtk_widget_set_valign (child, GTK_ALIGN_END);
+
+  check1 = gtk_check_button_new_with_label ("Show main");
+  g_object_bind_property (main_child, "visible", check1, "active", G_BINDING_BIDIRECTIONAL);
+
+  check2 = gtk_check_button_new_with_label ("Show overlay");
+  g_object_bind_property (child, "visible", check2, "active", G_BINDING_BIDIRECTIONAL);
+  gtk_container_add (GTK_CONTAINER (main_child), label);
+  gtk_container_add (GTK_CONTAINER (overlay), main_child);
+  gtk_overlay_add_overlay (GTK_OVERLAY (overlay), child);
+  gtk_grid_attach (GTK_GRID (grid), overlay, 1, 0, 1, 3);
+  gtk_container_add (GTK_CONTAINER (win), grid);
+
+  gtk_grid_attach (GTK_GRID (grid), check1, 0, 0, 1, 1);
+  gtk_grid_attach (GTK_GRID (grid), check2, 0, 1, 1, 1);
+  child = gtk_label_new ("");
+  gtk_widget_set_vexpand (child, TRUE);
+  gtk_grid_attach (GTK_GRID (grid), child, 0, 2, 1, 1);
+
+  return win;
+}
+
+int
+main (int argc, char *argv[])
+{
+  GtkWidget *win1;
+  GtkWidget *win2;
+  GtkWidget *win3;
+  GtkWidget *win4;
+  GtkWidget *win5;
+  GtkWidget *win6;
+  GtkWidget *win7;
+
+  gtk_init (&argc, &argv);
+
+  if (g_getenv ("RTL"))
+    gtk_widget_set_default_direction (GTK_TEXT_DIR_RTL);
+
+  win1 = test_nonzerox ();
+  gtk_widget_show_all (win1);
+
+  win2 = test_relative ();
+  gtk_widget_show_all (win2);
+
+  win3 = test_fullwidth ();
+  gtk_widget_show_all (win3);
+
+  win4 = test_scrolling ();
+  gtk_widget_show_all (win4);
+
+  win5 = test_builder ();
+  gtk_widget_show_all (win5);
+
+  win6 = test_chase ();
+  gtk_widget_show_all (win6);
+
+  win7 = test_stacking ();
+  gtk_widget_show_all (win7);
+
+  gtk_main ();
+
+  return 0;
+}