path: root/gtk/gtkscrolledwindow.c

/* GTK - The GIMP Toolkit
 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * 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.
 */

/*
 * Modified by the GTK+ Team and others 1997-2000.  See the AUTHORS
 * file for a list of people on the GTK+ Team.  See the ChangeLog
 * files for a list of changes.  These files are distributed with
 * GTK+ at ftp://ftp.gtk.org/pub/gtk/.
 */

#include "config.h"
#include <math.h>
#include <gdk/gdkkeysyms.h>
#include "gtkbindings.h"
#include "gtkmarshalers.h"
#include "gtkscrolledwindow.h"
#include "gtkwindow.h"
#include "gtktypeutils.h"
#include "gtkprivate.h"
#include "gtkintl.h"


/**
 * SECTION:gtkscrolledwindow
 * @Short_description: Adds scrollbars to its child widget
 * @Title: GtkScrolledWindow
 * @See_also: #GtkViewport, #GtkAdjustment, #GtkWidgetClass
 *
 * #GtkScrolledWindow is a #GtkBin subclass: it's a container
 * the accepts a single child widget. #GtkScrolledWindow adds scrollbars
 * to the child widget and optionally draws a beveled frame around the
 * child widget.
 *
 * The scrolled window can work in two ways. Some widgets have native
 * scrolling support; these widgets have "slots" for #GtkAdjustment
 * objects.
 * <footnote><para>The scrolled window installs #GtkAdjustment objects in
 * the child window's slots using the set_scroll_adjustments_signal,
 * found in #GtkWidgetClass. (Conceptually, these widgets implement a
 * "Scrollable" interface; because GTK+ 1.2 lacked interface support in
 * the object system, this interface is hackily implemented as a signal
 * in #GtkWidgetClass. The GTK+ 2.0 object system would allow a clean
 * implementation, but it wasn't worth breaking the
 * API.)</para></footnote>
 * Widgets with native scroll support include #GtkTreeView, #GtkTextView,
 * and #GtkLayout.
 *
 * For widgets that lack native scrolling support, the #GtkViewport
 * widget acts as an adaptor class, implementing scrollability for child
 * widgets that lack their own scrolling capabilities. Use #GtkViewport
 * to scroll child widgets such as #GtkTable, #GtkBox, and so on.
 *
 * If a widget has native scrolling abilities, it can be added to the
 * #GtkScrolledWindow with gtk_container_add(). If a widget does not, you
 * must first add the widget to a #GtkViewport, then add the #GtkViewport
 * to the scrolled window. The convenience function
 * gtk_scrolled_window_add_with_viewport() does exactly this, so you can
 * ignore the presence of the viewport.
 *
 * The position of the scrollbars is controlled by the scroll
 * adjustments. See #GtkAdjustment for the fields in an adjustment - for
 * #GtkScrollbar, used by #GtkScrolledWindow, the "value" field
 * represents the position of the scrollbar, which must be between the
 * "lower" field and "upper - page_size." The "page_size" field
 * represents the size of the visible scrollable area. The
 * "step_increment" and "page_increment" fields are used when the user
 * asks to step down (using the small stepper arrows) or page down (using
 * for example the PageDown key).
 *
 * If a #GtkScrolledWindow doesn't behave quite as you would like, or
 * doesn't have exactly the right layout, it's very possible to set up
 * your own scrolling with #GtkScrollbar and for example a #GtkTable.
 */


/* scrolled window policy and size requisition handling:
 *
 * gtk size requisition works as follows:
 *   a widget upon size-request reports the width and height that it finds
 *   to be best suited to display its contents, including children.
 *   the width and/or height reported from a widget upon size requisition
 *   may be overidden by the user by specifying a width and/or height
 *   other than 0 through gtk_widget_set_size_request().
 *
 * a scrolled window needs (for implementing all three policy types) to
 * request its width and height based on two different rationales.
 * 1)   the user wants the scrolled window to just fit into the space
 *      that it gets allocated for a specifc dimension.
 * 1.1) this does not apply if the user specified a concrete value
 *      value for that specific dimension by either specifying usize for the
 *      scrolled window or for its child.
 * 2)   the user wants the scrolled window to take as much space up as
 *      is desired by the child for a specifc dimension (i.e. POLICY_NEVER).
 *
 * also, kinda obvious:
 * 3)   a user would certainly not have choosen a scrolled window as a container
 *      for the child, if the resulting allocation takes up more space than the
 *      child would have allocated without the scrolled window.
 *
 * conclusions:
 * A) from 1) follows: the scrolled window shouldn't request more space for a
 *    specifc dimension than is required at minimum.
 * B) from 1.1) follows: the requisition may be overidden by usize of the scrolled
 *    window (done automatically) or by usize of the child (needs to be checked).
 * C) from 2) follows: for POLICY_NEVER, the scrolled window simply reports the
 *    child's dimension.
 * D) from 3) follows: the scrolled window child's minimum width and minimum height
 *    under A) at least correspond to the space taken up by its scrollbars.
 */

#define DEFAULT_SCROLLBAR_SPACING  3

struct _GtkScrolledWindowPrivate
{
  GtkCornerType  real_window_placement;
  GtkWidget     *hscrollbar;
  GtkWidget     *vscrollbar;

  gboolean window_placement_set;

  guint16  shadow_type;

  guint    hscrollbar_policy      : 2;
  guint    vscrollbar_policy      : 2;
  guint    hscrollbar_visible     : 1;
  guint    vscrollbar_visible     : 1;
  guint    window_placement       : 2;
  guint    focus_out              : 1;   /* Flag used by ::move-focus-out implementation */
};


enum {
  PROP_0,
  PROP_HADJUSTMENT,
  PROP_VADJUSTMENT,
  PROP_HSCROLLBAR_POLICY,
  PROP_VSCROLLBAR_POLICY,
  PROP_WINDOW_PLACEMENT,
  PROP_WINDOW_PLACEMENT_SET,
  PROP_SHADOW_TYPE
};

/* Signals */
enum
{
  SCROLL_CHILD,
  MOVE_FOCUS_OUT,
  LAST_SIGNAL
};

static void     gtk_scrolled_window_set_property       (GObject           *object,
                                                        guint              prop_id,
                                                        const GValue      *value,
                                                        GParamSpec        *pspec);
static void     gtk_scrolled_window_get_property       (GObject           *object,
                                                        guint              prop_id,
                                                        GValue            *value,
                                                        GParamSpec        *pspec);

static void     gtk_scrolled_window_destroy            (GtkWidget         *widget);
static void     gtk_scrolled_window_screen_changed     (GtkWidget         *widget,
                                                        GdkScreen         *previous_screen);
static gboolean gtk_scrolled_window_draw               (GtkWidget         *widget,
                                                        cairo_t           *cr);
static void     gtk_scrolled_window_size_allocate      (GtkWidget         *widget,
                                                        GtkAllocation     *allocation);
static gboolean gtk_scrolled_window_scroll_event       (GtkWidget         *widget,
                                                        GdkEventScroll    *event);
static gboolean gtk_scrolled_window_focus              (GtkWidget         *widget,
                                                        GtkDirectionType   direction);
static void     gtk_scrolled_window_add                (GtkContainer      *container,
                                                        GtkWidget         *widget);
static void     gtk_scrolled_window_remove             (GtkContainer      *container,
                                                        GtkWidget         *widget);
static void     gtk_scrolled_window_forall             (GtkContainer      *container,
                                                        gboolean           include_internals,
                                                        GtkCallback        callback,
                                                        gpointer           callback_data);
static gboolean gtk_scrolled_window_scroll_child       (GtkScrolledWindow *scrolled_window,
                                                        GtkScrollType      scroll,
                                                        gboolean           horizontal);
static void     gtk_scrolled_window_move_focus_out     (GtkScrolledWindow *scrolled_window,
                                                        GtkDirectionType   direction_type);

static void     gtk_scrolled_window_relative_allocation(GtkWidget         *widget,
                                                        GtkAllocation     *allocation);
static void     gtk_scrolled_window_adjustment_changed (GtkAdjustment     *adjustment,
                                                        gpointer           data);

static void  gtk_scrolled_window_update_real_placement (GtkScrolledWindow *scrolled_window);

static void  gtk_scrolled_window_get_preferred_width   (GtkWidget           *widget,
							gint                *minimum_size,
							gint                *natural_size);
static void  gtk_scrolled_window_get_preferred_height  (GtkWidget           *widget,
							gint                *minimum_size,
							gint                *natural_size);
static void  gtk_scrolled_window_get_preferred_height_for_width  (GtkWidget           *layout,
							gint                 width,
							gint                *minimum_height,
							gint                *natural_height);
static void  gtk_scrolled_window_get_preferred_width_for_height  (GtkWidget           *layout,
							gint                 width,
							gint                *minimum_height,
							gint                *natural_height);

static guint signals[LAST_SIGNAL] = {0};

G_DEFINE_TYPE (GtkScrolledWindow, gtk_scrolled_window, GTK_TYPE_BIN)


static void
add_scroll_binding (GtkBindingSet  *binding_set,
		    guint           keyval,
		    GdkModifierType mask,
		    GtkScrollType   scroll,
		    gboolean        horizontal)
{
  guint keypad_keyval = keyval - GDK_KEY_Left + GDK_KEY_KP_Left;
  
  gtk_binding_entry_add_signal (binding_set, keyval, mask,
                                "scroll-child", 2,
                                GTK_TYPE_SCROLL_TYPE, scroll,
				G_TYPE_BOOLEAN, horizontal);
  gtk_binding_entry_add_signal (binding_set, keypad_keyval, mask,
                                "scroll-child", 2,
                                GTK_TYPE_SCROLL_TYPE, scroll,
				G_TYPE_BOOLEAN, horizontal);
}

static void
add_tab_bindings (GtkBindingSet    *binding_set,
		  GdkModifierType   modifiers,
		  GtkDirectionType  direction)
{
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_Tab, modifiers,
                                "move-focus-out", 1,
                                GTK_TYPE_DIRECTION_TYPE, direction);
  gtk_binding_entry_add_signal (binding_set, GDK_KEY_KP_Tab, modifiers,
                                "move-focus-out", 1,
                                GTK_TYPE_DIRECTION_TYPE, direction);
}

static void
gtk_scrolled_window_class_init (GtkScrolledWindowClass *class)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (class);
  GtkWidgetClass *widget_class;
  GtkContainerClass *container_class;
  GtkBindingSet *binding_set;

  widget_class = (GtkWidgetClass*) class;
  container_class = (GtkContainerClass*) class;

  gobject_class->set_property = gtk_scrolled_window_set_property;
  gobject_class->get_property = gtk_scrolled_window_get_property;

  widget_class->destroy = gtk_scrolled_window_destroy;
  widget_class->screen_changed = gtk_scrolled_window_screen_changed;
  widget_class->draw = gtk_scrolled_window_draw;
  widget_class->size_allocate = gtk_scrolled_window_size_allocate;
  widget_class->scroll_event = gtk_scrolled_window_scroll_event;
  widget_class->focus = gtk_scrolled_window_focus;
  widget_class->get_preferred_width = gtk_scrolled_window_get_preferred_width;
  widget_class->get_preferred_height = gtk_scrolled_window_get_preferred_height;
  widget_class->get_preferred_height_for_width = gtk_scrolled_window_get_preferred_height_for_width;
  widget_class->get_preferred_width_for_height = gtk_scrolled_window_get_preferred_width_for_height;

  container_class->add = gtk_scrolled_window_add;
  container_class->remove = gtk_scrolled_window_remove;
  container_class->forall = gtk_scrolled_window_forall;
  gtk_container_class_handle_border_width (container_class);

  class->scrollbar_spacing = -1;

  class->scroll_child = gtk_scrolled_window_scroll_child;
  class->move_focus_out = gtk_scrolled_window_move_focus_out;
  
  g_object_class_install_property (gobject_class,
				   PROP_HADJUSTMENT,
				   g_param_spec_object ("hadjustment",
							P_("Horizontal Adjustment"),
							P_("The GtkAdjustment for the horizontal position"),
							GTK_TYPE_ADJUSTMENT,
							GTK_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (gobject_class,
				   PROP_VADJUSTMENT,
				   g_param_spec_object ("vadjustment",
							P_("Vertical Adjustment"),
							P_("The GtkAdjustment for the vertical position"),
							GTK_TYPE_ADJUSTMENT,
							GTK_PARAM_READWRITE | G_PARAM_CONSTRUCT));
  g_object_class_install_property (gobject_class,
                                   PROP_HSCROLLBAR_POLICY,
                                   g_param_spec_enum ("hscrollbar-policy",
                                                      P_("Horizontal Scrollbar Policy"),
                                                      P_("When the horizontal scrollbar is displayed"),
						      GTK_TYPE_POLICY_TYPE,
						      GTK_POLICY_AUTOMATIC,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  g_object_class_install_property (gobject_class,
                                   PROP_VSCROLLBAR_POLICY,
                                   g_param_spec_enum ("vscrollbar-policy",
                                                      P_("Vertical Scrollbar Policy"),
                                                      P_("When the vertical scrollbar is displayed"),
						      GTK_TYPE_POLICY_TYPE,
						      GTK_POLICY_AUTOMATIC,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));

  g_object_class_install_property (gobject_class,
                                   PROP_WINDOW_PLACEMENT,
                                   g_param_spec_enum ("window-placement",
                                                      P_("Window Placement"),
                                                      P_("Where the contents are located with respect to the scrollbars. This property only takes effect if \"window-placement-set\" is TRUE."),
						      GTK_TYPE_CORNER_TYPE,
						      GTK_CORNER_TOP_LEFT,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  
  /**
   * GtkScrolledWindow:window-placement-set:
   *
   * Whether "window-placement" should be used to determine the location 
   * of the contents with respect to the scrollbars. Otherwise, the 
   * "gtk-scrolled-window-placement" setting is used.
   *
   * Since: 2.10
   */
  g_object_class_install_property (gobject_class,
                                   PROP_WINDOW_PLACEMENT_SET,
                                   g_param_spec_boolean ("window-placement-set",
					   		 P_("Window Placement Set"),
							 P_("Whether \"window-placement\" should be used to determine the location of the contents with respect to the scrollbars."),
							 FALSE,
							 GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));
  g_object_class_install_property (gobject_class,
                                   PROP_SHADOW_TYPE,
                                   g_param_spec_enum ("shadow-type",
                                                      P_("Shadow Type"),
                                                      P_("Style of bevel around the contents"),
						      GTK_TYPE_SHADOW_TYPE,
						      GTK_SHADOW_NONE,
                                                      GTK_PARAM_READABLE | GTK_PARAM_WRITABLE));

  /**
   * GtkScrolledWindow:scrollbars-within-bevel:
   *
   * Whether to place scrollbars within the scrolled window's bevel.
   *
   * Since: 2.12
   */
  gtk_widget_class_install_style_property (widget_class,
					   g_param_spec_boolean ("scrollbars-within-bevel",
							         P_("Scrollbars within bevel"),
							         P_("Place scrollbars within the scrolled window's bevel"),
							         FALSE,
							         GTK_PARAM_READABLE));

  gtk_widget_class_install_style_property (widget_class,
					   g_param_spec_int ("scrollbar-spacing",
							     P_("Scrollbar spacing"),
							     P_("Number of pixels between the scrollbars and the scrolled window"),
							     0,
							     G_MAXINT,
							     DEFAULT_SCROLLBAR_SPACING,
							     GTK_PARAM_READABLE));

  /**
   * GtkSettings:gtk-scrolled-window-placement:
   *
   * Where the contents of scrolled windows are located with respect to the 
   * scrollbars, if not overridden by the scrolled window's own placement.
   *
   * Since: 2.10
   */
  gtk_settings_install_property (g_param_spec_enum ("gtk-scrolled-window-placement",
						    P_("Scrolled Window Placement"),
						    P_("Where the contents of scrolled windows are located with respect to the scrollbars, if not overridden by the scrolled window's own placement."),
						    GTK_TYPE_CORNER_TYPE,
						    GTK_CORNER_TOP_LEFT,
						    G_PARAM_READABLE | G_PARAM_WRITABLE));

  /**
   * GtkScrolledWindow::scroll-child:
   * @scrolled_window: a #GtkScrolledWindow
   * @scroll: a #GtkScrollType describing how much to scroll
   * @horizontal: whether the keybinding scrolls the child
   *   horizontally or not
   *
   * The ::scroll-child signal is a
   * <link linkend="keybinding-signals">keybinding signal</link>
   * which gets emitted when a keybinding that scrolls is pressed.
   * The horizontal or vertical adjustment is updated which triggers a
   * signal that the scrolled windows child may listen to and scroll itself.
   */
  signals[SCROLL_CHILD] =
    g_signal_new (I_("scroll-child"),
                  G_TYPE_FROM_CLASS (gobject_class),
                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                  G_STRUCT_OFFSET (GtkScrolledWindowClass, scroll_child),
                  NULL, NULL,
                  _gtk_marshal_BOOLEAN__ENUM_BOOLEAN,
                  G_TYPE_BOOLEAN, 2,
                  GTK_TYPE_SCROLL_TYPE,
		  G_TYPE_BOOLEAN);

  /**
   * GtkScrolledWindow::move-focus-out:
   * @scrolled_window: a #GtkScrolledWindow
   * @direction_type: either %GTK_DIR_TAB_FORWARD or
   *   %GTK_DIR_TAB_BACKWARD
   *
   * The ::move-focus-out signal is a
   * <link linkend="keybinding-signals">keybinding signal</link>
   * which gets emitted when focus is moved away from the scrolled
   * window by a keybinding.
   * The #GtkWidget::move-focus signal is emitted with @direction_type
   * on this scrolled windows toplevel parent in the container hierarchy.
   * The default bindings for this signal are
   * <keycombo><keycap>Tab</keycap><keycap>Ctrl</keycap></keycombo>
   * and
   * <keycombo><keycap>Tab</keycap><keycap>Ctrl</keycap><keycap>Shift</keycap></keycombo>.
   */
  signals[MOVE_FOCUS_OUT] =
    g_signal_new (I_("move-focus-out"),
                  G_TYPE_FROM_CLASS (gobject_class),
                  G_SIGNAL_RUN_LAST | G_SIGNAL_ACTION,
                  G_STRUCT_OFFSET (GtkScrolledWindowClass, move_focus_out),
                  NULL, NULL,
                  _gtk_marshal_VOID__ENUM,
                  G_TYPE_NONE, 1,
                  GTK_TYPE_DIRECTION_TYPE);
  
  binding_set = gtk_binding_set_by_class (class);

  add_scroll_binding (binding_set, GDK_KEY_Left,  GDK_CONTROL_MASK, GTK_SCROLL_STEP_BACKWARD, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Right, GDK_CONTROL_MASK, GTK_SCROLL_STEP_FORWARD,  TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Up,    GDK_CONTROL_MASK, GTK_SCROLL_STEP_BACKWARD, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_Down,  GDK_CONTROL_MASK, GTK_SCROLL_STEP_FORWARD,  FALSE);

  add_scroll_binding (binding_set, GDK_KEY_Page_Up,   GDK_CONTROL_MASK, GTK_SCROLL_PAGE_BACKWARD, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Down, GDK_CONTROL_MASK, GTK_SCROLL_PAGE_FORWARD,  TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Up,   0,                GTK_SCROLL_PAGE_BACKWARD, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_Page_Down, 0,                GTK_SCROLL_PAGE_FORWARD,  FALSE);

  add_scroll_binding (binding_set, GDK_KEY_Home, GDK_CONTROL_MASK, GTK_SCROLL_START, TRUE);
  add_scroll_binding (binding_set, GDK_KEY_End,  GDK_CONTROL_MASK, GTK_SCROLL_END,   TRUE);
  add_scroll_binding (binding_set, GDK_KEY_Home, 0,                GTK_SCROLL_START, FALSE);
  add_scroll_binding (binding_set, GDK_KEY_End,  0,                GTK_SCROLL_END,   FALSE);

  add_tab_bindings (binding_set, GDK_CONTROL_MASK, GTK_DIR_TAB_FORWARD);
  add_tab_bindings (binding_set, GDK_CONTROL_MASK | GDK_SHIFT_MASK, GTK_DIR_TAB_BACKWARD);

  g_type_class_add_private (class, sizeof (GtkScrolledWindowPrivate));
}

static void
gtk_scrolled_window_init (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  scrolled_window->priv = priv = G_TYPE_INSTANCE_GET_PRIVATE (scrolled_window,
                                                              GTK_TYPE_SCROLLED_WINDOW,
                                                              GtkScrolledWindowPrivate);

  gtk_widget_set_has_window (GTK_WIDGET (scrolled_window), FALSE);
  gtk_widget_set_can_focus (GTK_WIDGET (scrolled_window), TRUE);

  priv->hscrollbar = NULL;
  priv->vscrollbar = NULL;
  priv->hscrollbar_policy = GTK_POLICY_AUTOMATIC;
  priv->vscrollbar_policy = GTK_POLICY_AUTOMATIC;
  priv->hscrollbar_visible = FALSE;
  priv->vscrollbar_visible = FALSE;
  priv->focus_out = FALSE;
  priv->window_placement = GTK_CORNER_TOP_LEFT;
  gtk_scrolled_window_update_real_placement (scrolled_window);
}

/**
 * gtk_scrolled_window_new:
 * @hadjustment: (allow-none): horizontal adjustment
 * @vadjustment: (allow-none): vertical adjustment
 *
 * Creates a new scrolled window.
 *
 * The two arguments are the scrolled window's adjustments; these will be
 * shared with the scrollbars and the child widget to keep the bars in sync 
 * with the child. Usually you want to pass %NULL for the adjustments, which 
 * will cause the scrolled window to create them for you.
 *
 * Returns: a new scrolled window
 */
GtkWidget*
gtk_scrolled_window_new (GtkAdjustment *hadjustment,
			 GtkAdjustment *vadjustment)
{
  GtkWidget *scrolled_window;

  if (hadjustment)
    g_return_val_if_fail (GTK_IS_ADJUSTMENT (hadjustment), NULL);

  if (vadjustment)
    g_return_val_if_fail (GTK_IS_ADJUSTMENT (vadjustment), NULL);

  scrolled_window = g_object_new (GTK_TYPE_SCROLLED_WINDOW,
				    "hadjustment", hadjustment,
				    "vadjustment", vadjustment,
				    NULL);

  return scrolled_window;
}

/**
 * gtk_scrolled_window_set_hadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * @hadjustment: horizontal scroll adjustment
 *
 * Sets the #GtkAdjustment for the horizontal scrollbar.
 */
void
gtk_scrolled_window_set_hadjustment (GtkScrolledWindow *scrolled_window,
				     GtkAdjustment     *hadjustment)
{
  GtkScrolledWindowPrivate *priv;
  GtkBin *bin;
  GtkWidget *child;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  if (hadjustment)
    g_return_if_fail (GTK_IS_ADJUSTMENT (hadjustment));
  else
    hadjustment = (GtkAdjustment*) g_object_new (GTK_TYPE_ADJUSTMENT, NULL);

  bin = GTK_BIN (scrolled_window);
  priv = scrolled_window->priv;

  if (!priv->hscrollbar)
    {
      gtk_widget_push_composite_child ();
      priv->hscrollbar = gtk_hscrollbar_new (hadjustment);
      gtk_widget_set_composite_name (priv->hscrollbar, "hscrollbar");
      gtk_widget_pop_composite_child ();

      gtk_widget_set_parent (priv->hscrollbar, GTK_WIDGET (scrolled_window));
      g_object_ref (priv->hscrollbar);
      gtk_widget_show (priv->hscrollbar);
    }
  else
    {
      GtkAdjustment *old_adjustment;
      
      old_adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
      if (old_adjustment == hadjustment)
	return;

      g_signal_handlers_disconnect_by_func (old_adjustment,
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_range_set_adjustment (GTK_RANGE (priv->hscrollbar),
				hadjustment);
    }
  hadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
  g_signal_connect (hadjustment,
		    "changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_changed),
		    scrolled_window);
  gtk_scrolled_window_adjustment_changed (hadjustment, scrolled_window);

  child = gtk_bin_get_child (bin);
  if (child)
    gtk_widget_set_scroll_adjustments (child,
				       gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)),
				       gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)));

  g_object_notify (G_OBJECT (scrolled_window), "hadjustment");
}

/**
 * gtk_scrolled_window_set_vadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * @vadjustment: vertical scroll adjustment
 *
 * Sets the #GtkAdjustment for the vertical scrollbar.
 */
void
gtk_scrolled_window_set_vadjustment (GtkScrolledWindow *scrolled_window,
				     GtkAdjustment     *vadjustment)
{
  GtkScrolledWindowPrivate *priv;
  GtkBin *bin;
  GtkWidget *child;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  if (vadjustment)
    g_return_if_fail (GTK_IS_ADJUSTMENT (vadjustment));
  else
    vadjustment = (GtkAdjustment*) g_object_new (GTK_TYPE_ADJUSTMENT, NULL);

  bin = GTK_BIN (scrolled_window);
  priv = scrolled_window->priv;

  if (!priv->vscrollbar)
    {
      gtk_widget_push_composite_child ();
      priv->vscrollbar = gtk_vscrollbar_new (vadjustment);
      gtk_widget_set_composite_name (priv->vscrollbar, "vscrollbar");
      gtk_widget_pop_composite_child ();

      gtk_widget_set_parent (priv->vscrollbar, GTK_WIDGET (scrolled_window));
      g_object_ref (priv->vscrollbar);
      gtk_widget_show (priv->vscrollbar);
    }
  else
    {
      GtkAdjustment *old_adjustment;
      
      old_adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
      if (old_adjustment == vadjustment)
	return;

      g_signal_handlers_disconnect_by_func (old_adjustment,
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_range_set_adjustment (GTK_RANGE (priv->vscrollbar),
				vadjustment);
    }
  vadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
  g_signal_connect (vadjustment,
		    "changed",
		    G_CALLBACK (gtk_scrolled_window_adjustment_changed),
		    scrolled_window);
  gtk_scrolled_window_adjustment_changed (vadjustment, scrolled_window);

  child = gtk_bin_get_child (bin);
  if (child)
    gtk_widget_set_scroll_adjustments (child,
				       gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)),
				       gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)));

  g_object_notify (G_OBJECT (scrolled_window), "vadjustment");
}

/**
 * gtk_scrolled_window_get_hadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Returns the horizontal scrollbar's adjustment, used to connect the
 * horizontal scrollbar to the child widget's horizontal scroll
 * functionality.
 *
 * Returns: (transfer none): the horizontal #GtkAdjustment
 */
GtkAdjustment*
gtk_scrolled_window_get_hadjustment (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  priv = scrolled_window->priv;

  return (priv->hscrollbar ?
	  gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)) :
	  NULL);
}

/**
 * gtk_scrolled_window_get_vadjustment:
 * @scrolled_window: a #GtkScrolledWindow
 * 
 * Returns the vertical scrollbar's adjustment, used to connect the
 * vertical scrollbar to the child widget's vertical scroll functionality.
 * 
 * Returns: (transfer none): the vertical #GtkAdjustment
 */
GtkAdjustment*
gtk_scrolled_window_get_vadjustment (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  priv = scrolled_window->priv;

  return (priv->vscrollbar ?
	  gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)) :
	  NULL);
}

/**
 * gtk_scrolled_window_get_hscrollbar:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Returns the horizontal scrollbar of @scrolled_window.
 *
 * Returns: (transfer none): the horizontal scrollbar of the scrolled window,
 *     or %NULL if it does not have one.
 *
 * Since: 2.8
 */
GtkWidget*
gtk_scrolled_window_get_hscrollbar (GtkScrolledWindow *scrolled_window)
{
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  return scrolled_window->priv->hscrollbar;
}

/**
 * gtk_scrolled_window_get_vscrollbar:
 * @scrolled_window: a #GtkScrolledWindow
 * 
 * Returns the vertical scrollbar of @scrolled_window.
 *
 * Returns: (transfer none): the vertical scrollbar of the scrolled window,
 *     or %NULL if it does not have one.
 *
 * Since: 2.8
 */
GtkWidget*
gtk_scrolled_window_get_vscrollbar (GtkScrolledWindow *scrolled_window)
{
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), NULL);

  return scrolled_window->priv->vscrollbar;
}

/**
 * gtk_scrolled_window_set_policy:
 * @scrolled_window: a #GtkScrolledWindow
 * @hscrollbar_policy: policy for horizontal bar
 * @vscrollbar_policy: policy for vertical bar
 * 
 * Sets the scrollbar policy for the horizontal and vertical scrollbars.
 *
 * The policy determines when the scrollbar should appear; it is a value
 * from the #GtkPolicyType enumeration. If %GTK_POLICY_ALWAYS, the
 * scrollbar is always present; if %GTK_POLICY_NEVER, the scrollbar is
 * never present; if %GTK_POLICY_AUTOMATIC, the scrollbar is present only
 * if needed (that is, if the slider part of the bar would be smaller
 * than the trough - the display is larger than the page size).
 */
void
gtk_scrolled_window_set_policy (GtkScrolledWindow *scrolled_window,
				GtkPolicyType      hscrollbar_policy,
				GtkPolicyType      vscrollbar_policy)
{
  GtkScrolledWindowPrivate *priv;
  GObject *object = G_OBJECT (scrolled_window);
  
  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));

  priv = scrolled_window->priv;

  if ((priv->hscrollbar_policy != hscrollbar_policy) ||
      (priv->vscrollbar_policy != vscrollbar_policy))
    {
      priv->hscrollbar_policy = hscrollbar_policy;
      priv->vscrollbar_policy = vscrollbar_policy;

      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));

      g_object_freeze_notify (object);
      g_object_notify (object, "hscrollbar-policy");
      g_object_notify (object, "vscrollbar-policy");
      g_object_thaw_notify (object);
    }
}

/**
 * gtk_scrolled_window_get_policy:
 * @scrolled_window: a #GtkScrolledWindow
 * @hscrollbar_policy: location to store the policy for the horizontal 
 *     scrollbar, or %NULL.
 * @vscrollbar_policy: location to store the policy for the vertical
 *     scrollbar, or %NULL.
 * 
 * Retrieves the current policy values for the horizontal and vertical
 * scrollbars. See gtk_scrolled_window_set_policy().
 */
void
gtk_scrolled_window_get_policy (GtkScrolledWindow *scrolled_window,
				GtkPolicyType     *hscrollbar_policy,
				GtkPolicyType     *vscrollbar_policy)
{
  GtkScrolledWindowPrivate *priv;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));

  priv = scrolled_window->priv;

  if (hscrollbar_policy)
    *hscrollbar_policy = priv->hscrollbar_policy;
  if (vscrollbar_policy)
    *vscrollbar_policy = priv->vscrollbar_policy;
}

static void
gtk_scrolled_window_update_real_placement (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkSettings *settings;

  settings = gtk_widget_get_settings (GTK_WIDGET (scrolled_window));

  if (priv->window_placement_set || settings == NULL)
    priv->real_window_placement = priv->window_placement;
  else
    g_object_get (settings,
		  "gtk-scrolled-window-placement",
		  &priv->real_window_placement,
		  NULL);
}

static void
gtk_scrolled_window_set_placement_internal (GtkScrolledWindow *scrolled_window,
					    GtkCornerType      window_placement)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  if (priv->window_placement != window_placement)
    {
      priv->window_placement = window_placement;

      gtk_scrolled_window_update_real_placement (scrolled_window);
      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
      
      g_object_notify (G_OBJECT (scrolled_window), "window-placement");
    }
}

static void
gtk_scrolled_window_set_placement_set (GtkScrolledWindow *scrolled_window,
				       gboolean           placement_set,
				       gboolean           emit_resize)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  if (priv->window_placement_set != placement_set)
    {
      priv->window_placement_set = placement_set;

      gtk_scrolled_window_update_real_placement (scrolled_window);
      if (emit_resize)
        gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));

      g_object_notify (G_OBJECT (scrolled_window), "window-placement-set");
    }
}

/**
 * gtk_scrolled_window_set_placement:
 * @scrolled_window: a #GtkScrolledWindow
 * @window_placement: position of the child window
 *
 * Sets the placement of the contents with respect to the scrollbars
 * for the scrolled window.
 * 
 * The default is %GTK_CORNER_TOP_LEFT, meaning the child is
 * in the top left, with the scrollbars underneath and to the right.
 * Other values in #GtkCornerType are %GTK_CORNER_TOP_RIGHT,
 * %GTK_CORNER_BOTTOM_LEFT, and %GTK_CORNER_BOTTOM_RIGHT.
 *
 * See also gtk_scrolled_window_get_placement() and
 * gtk_scrolled_window_unset_placement().
 */
void
gtk_scrolled_window_set_placement (GtkScrolledWindow *scrolled_window,
				   GtkCornerType      window_placement)
{
  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));

  gtk_scrolled_window_set_placement_set (scrolled_window, TRUE, FALSE);
  gtk_scrolled_window_set_placement_internal (scrolled_window, window_placement);
}

/**
 * gtk_scrolled_window_get_placement:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Gets the placement of the contents with respect to the scrollbars
 * for the scrolled window. See gtk_scrolled_window_set_placement().
 *
 * Return value: the current placement value.
 *
 * See also gtk_scrolled_window_set_placement() and
 * gtk_scrolled_window_unset_placement().
 **/
GtkCornerType
gtk_scrolled_window_get_placement (GtkScrolledWindow *scrolled_window)
{
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), GTK_CORNER_TOP_LEFT);

  return scrolled_window->priv->window_placement;
}

/**
 * gtk_scrolled_window_unset_placement:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Unsets the placement of the contents with respect to the scrollbars
 * for the scrolled window. If no window placement is set for a scrolled
 * window, it obeys the "gtk-scrolled-window-placement" XSETTING.
 *
 * See also gtk_scrolled_window_set_placement() and
 * gtk_scrolled_window_get_placement().
 *
 * Since: 2.10
 **/
void
gtk_scrolled_window_unset_placement (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowPrivate *priv;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));

  priv = scrolled_window->priv;

  if (priv->window_placement_set)
    {
      priv->window_placement_set = FALSE;

      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));

      g_object_notify (G_OBJECT (scrolled_window), "window-placement-set");
    }
}

/**
 * gtk_scrolled_window_set_shadow_type:
 * @scrolled_window: a #GtkScrolledWindow
 * @type: kind of shadow to draw around scrolled window contents
 *
 * Changes the type of shadow drawn around the contents of
 * @scrolled_window.
 * 
 **/
void
gtk_scrolled_window_set_shadow_type (GtkScrolledWindow *scrolled_window,
				     GtkShadowType      type)
{
  GtkScrolledWindowPrivate *priv;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  g_return_if_fail (type >= GTK_SHADOW_NONE && type <= GTK_SHADOW_ETCHED_OUT);

  priv = scrolled_window->priv;

  if (priv->shadow_type != type)
    {
      priv->shadow_type = type;

      if (gtk_widget_is_drawable (GTK_WIDGET (scrolled_window)))
	gtk_widget_queue_draw (GTK_WIDGET (scrolled_window));

      gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));

      g_object_notify (G_OBJECT (scrolled_window), "shadow-type");
    }
}

/**
 * gtk_scrolled_window_get_shadow_type:
 * @scrolled_window: a #GtkScrolledWindow
 *
 * Gets the shadow type of the scrolled window. See 
 * gtk_scrolled_window_set_shadow_type().
 *
 * Return value: the current shadow type
 **/
GtkShadowType
gtk_scrolled_window_get_shadow_type (GtkScrolledWindow *scrolled_window)
{
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), GTK_SHADOW_NONE);

  return scrolled_window->priv->shadow_type;
}

static void
gtk_scrolled_window_destroy (GtkWidget *widget)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  if (priv->hscrollbar)
    {
      g_signal_handlers_disconnect_by_func (gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)),
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_widget_unparent (priv->hscrollbar);
      gtk_widget_destroy (priv->hscrollbar);
      g_object_unref (priv->hscrollbar);
      priv->hscrollbar = NULL;
    }
  if (priv->vscrollbar)
    {
      g_signal_handlers_disconnect_by_func (gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)),
					    gtk_scrolled_window_adjustment_changed,
					    scrolled_window);
      gtk_widget_unparent (priv->vscrollbar);
      gtk_widget_destroy (priv->vscrollbar);
      g_object_unref (priv->vscrollbar);
      priv->vscrollbar = NULL;
    }

  GTK_WIDGET_CLASS (gtk_scrolled_window_parent_class)->destroy (widget);
}

static void
gtk_scrolled_window_set_property (GObject      *object,
				  guint         prop_id,
				  const GValue *value,
				  GParamSpec   *pspec)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (object);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  switch (prop_id)
    {
    case PROP_HADJUSTMENT:
      gtk_scrolled_window_set_hadjustment (scrolled_window,
					   g_value_get_object (value));
      break;
    case PROP_VADJUSTMENT:
      gtk_scrolled_window_set_vadjustment (scrolled_window,
					   g_value_get_object (value));
      break;
    case PROP_HSCROLLBAR_POLICY:
      gtk_scrolled_window_set_policy (scrolled_window,
				      g_value_get_enum (value),
				      priv->vscrollbar_policy);
      break;
    case PROP_VSCROLLBAR_POLICY:
      gtk_scrolled_window_set_policy (scrolled_window,
				      priv->hscrollbar_policy,
				      g_value_get_enum (value));
      break;
    case PROP_WINDOW_PLACEMENT:
      gtk_scrolled_window_set_placement_internal (scrolled_window,
		      				  g_value_get_enum (value));
      break;
    case PROP_WINDOW_PLACEMENT_SET:
      gtk_scrolled_window_set_placement_set (scrolled_window,
		      			     g_value_get_boolean (value),
					     TRUE);
      break;
    case PROP_SHADOW_TYPE:
      gtk_scrolled_window_set_shadow_type (scrolled_window,
					   g_value_get_enum (value));
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
gtk_scrolled_window_get_property (GObject    *object,
				  guint       prop_id,
				  GValue     *value,
				  GParamSpec *pspec)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (object);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  switch (prop_id)
    {
    case PROP_HADJUSTMENT:
      g_value_set_object (value,
			  G_OBJECT (gtk_scrolled_window_get_hadjustment (scrolled_window)));
      break;
    case PROP_VADJUSTMENT:
      g_value_set_object (value,
			  G_OBJECT (gtk_scrolled_window_get_vadjustment (scrolled_window)));
      break;
    case PROP_HSCROLLBAR_POLICY:
      g_value_set_enum (value, priv->hscrollbar_policy);
      break;
    case PROP_VSCROLLBAR_POLICY:
      g_value_set_enum (value, priv->vscrollbar_policy);
      break;
    case PROP_WINDOW_PLACEMENT:
      g_value_set_enum (value, priv->window_placement);
      break;
    case PROP_WINDOW_PLACEMENT_SET:
      g_value_set_boolean (value, priv->window_placement_set);
      break;
    case PROP_SHADOW_TYPE:
      g_value_set_enum (value, priv->shadow_type);
      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
      break;
    }
}

static void
traverse_container (GtkWidget *widget,
		    gpointer   data)
{
  if (GTK_IS_SCROLLED_WINDOW (widget))
    {
      gtk_scrolled_window_update_real_placement (GTK_SCROLLED_WINDOW (widget));
      gtk_widget_queue_resize (widget);
    }
  else if (GTK_IS_CONTAINER (widget))
    gtk_container_forall (GTK_CONTAINER (widget), traverse_container, NULL);
}

static void
gtk_scrolled_window_settings_changed (GtkSettings *settings)
{
  GList *list, *l;

  list = gtk_window_list_toplevels ();

  for (l = list; l; l = l->next)
    gtk_container_forall (GTK_CONTAINER (l->data), 
			  traverse_container, NULL);

  g_list_free (list);
}

static void
gtk_scrolled_window_screen_changed (GtkWidget *widget,
				    GdkScreen *previous_screen)
{
  GtkSettings *settings;
  guint window_placement_connection;

  gtk_scrolled_window_update_real_placement (GTK_SCROLLED_WINDOW (widget));

  if (!gtk_widget_has_screen (widget))
    return;

  settings = gtk_widget_get_settings (widget);

  window_placement_connection = 
    GPOINTER_TO_UINT (g_object_get_data (G_OBJECT (settings), 
					 "gtk-scrolled-window-connection"));
  
  if (window_placement_connection)
    return;

  window_placement_connection =
    g_signal_connect (settings, "notify::gtk-scrolled-window-placement",
		      G_CALLBACK (gtk_scrolled_window_settings_changed), NULL);
  g_object_set_data (G_OBJECT (settings), 
		     I_("gtk-scrolled-window-connection"),
		     GUINT_TO_POINTER (window_placement_connection));
}

static gboolean
gtk_scrolled_window_draw (GtkWidget *widget,
                          cairo_t   *cr)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;

  if (priv->shadow_type != GTK_SHADOW_NONE)
    {
      GtkAllocation relative_allocation;
      GtkStyle *style;
      gboolean scrollbars_within_bevel;

      style = gtk_widget_get_style (widget);
      gtk_widget_style_get (widget, "scrollbars-within-bevel", &scrollbars_within_bevel, NULL);

      if (!scrollbars_within_bevel)
        {
          gtk_scrolled_window_relative_allocation (widget, &relative_allocation);

          relative_allocation.x -= style->xthickness;
          relative_allocation.y -= style->ythickness;
          relative_allocation.width += 2 * style->xthickness;
          relative_allocation.height += 2 * style->ythickness;
        }
      else
        {
          relative_allocation.x = 0;
          relative_allocation.y = 0;
          relative_allocation.width = gtk_widget_get_allocated_width (widget);
          relative_allocation.height = gtk_widget_get_allocated_height (widget);
        }

      gtk_paint_shadow (style,
                        cr,
			GTK_STATE_NORMAL, priv->shadow_type,
			widget, "scrolled_window",
                        relative_allocation.x,
                        relative_allocation.y,
			relative_allocation.width,
			relative_allocation.height);
    }

  GTK_WIDGET_CLASS (gtk_scrolled_window_parent_class)->draw (widget, cr);

  return FALSE;
}

static void
gtk_scrolled_window_forall (GtkContainer *container,
			    gboolean	  include_internals,
			    GtkCallback   callback,
			    gpointer      callback_data)
{
  GtkScrolledWindowPrivate *priv;
  GtkScrolledWindow *scrolled_window;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (container));
  g_return_if_fail (callback != NULL);

  GTK_CONTAINER_CLASS (gtk_scrolled_window_parent_class)->forall (container,
					      include_internals,
					      callback,
					      callback_data);
  if (include_internals)
    {
      scrolled_window = GTK_SCROLLED_WINDOW (container);
      priv = scrolled_window->priv;

      if (priv->vscrollbar)
	callback (priv->vscrollbar, callback_data);
      if (priv->hscrollbar)
	callback (priv->hscrollbar, callback_data);
    }
}

static gboolean
gtk_scrolled_window_scroll_child (GtkScrolledWindow *scrolled_window,
				  GtkScrollType      scroll,
				  gboolean           horizontal)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkAdjustment *adjustment = NULL;
  
  switch (scroll)
    {
    case GTK_SCROLL_STEP_UP:
      scroll = GTK_SCROLL_STEP_BACKWARD;
      horizontal = FALSE;
      break;
    case GTK_SCROLL_STEP_DOWN:
      scroll = GTK_SCROLL_STEP_FORWARD;
      horizontal = FALSE;
      break;
    case GTK_SCROLL_STEP_LEFT:
      scroll = GTK_SCROLL_STEP_BACKWARD;
      horizontal = TRUE;
      break;
    case GTK_SCROLL_STEP_RIGHT:
      scroll = GTK_SCROLL_STEP_FORWARD;
      horizontal = TRUE;
      break;
    case GTK_SCROLL_PAGE_UP:
      scroll = GTK_SCROLL_PAGE_BACKWARD;
      horizontal = FALSE;
      break;
    case GTK_SCROLL_PAGE_DOWN:
      scroll = GTK_SCROLL_PAGE_FORWARD;
      horizontal = FALSE;
      break;
    case GTK_SCROLL_PAGE_LEFT:
      scroll = GTK_SCROLL_STEP_BACKWARD;
      horizontal = TRUE;
      break;
    case GTK_SCROLL_PAGE_RIGHT:
      scroll = GTK_SCROLL_STEP_FORWARD;
      horizontal = TRUE;
      break;
    case GTK_SCROLL_STEP_BACKWARD:
    case GTK_SCROLL_STEP_FORWARD:
    case GTK_SCROLL_PAGE_BACKWARD:
    case GTK_SCROLL_PAGE_FORWARD:
    case GTK_SCROLL_START:
    case GTK_SCROLL_END:
      break;
    default:
      g_warning ("Invalid scroll type %u for GtkScrolledWindow::scroll-child", scroll);
      return FALSE;
    }

  if ((horizontal && (!priv->hscrollbar || !priv->hscrollbar_visible)) ||
      (!horizontal && (!priv->vscrollbar || !priv->vscrollbar_visible)))
    return FALSE;

  if (horizontal)
    {
      if (priv->hscrollbar)
	adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
    }
  else
    {
      if (priv->vscrollbar)
	adjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
    }

  if (adjustment)
    {
      gdouble value = adjustment->value;
      
      switch (scroll)
	{
	case GTK_SCROLL_STEP_FORWARD:
	  value += adjustment->step_increment;
	  break;
	case GTK_SCROLL_STEP_BACKWARD:
	  value -= adjustment->step_increment;
	  break;
	case GTK_SCROLL_PAGE_FORWARD:
	  value += adjustment->page_increment;
	  break;
	case GTK_SCROLL_PAGE_BACKWARD:
	  value -= adjustment->page_increment;
	  break;
	case GTK_SCROLL_START:
	  value = adjustment->lower;
	  break;
	case GTK_SCROLL_END:
	  value = adjustment->upper;
	  break;
	default:
	  g_assert_not_reached ();
	  break;
	}

      gtk_adjustment_set_value (adjustment, value);

      return TRUE;
    }

  return FALSE;
}

static void
gtk_scrolled_window_move_focus_out (GtkScrolledWindow *scrolled_window,
				    GtkDirectionType   direction_type)
{
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkWidget *toplevel;
  
  /* Focus out of the scrolled window entirely. We do this by setting
   * a flag, then propagating the focus motion to the notebook.
   */
  toplevel = gtk_widget_get_toplevel (GTK_WIDGET (scrolled_window));
  if (!gtk_widget_is_toplevel (toplevel))
    return;

  g_object_ref (scrolled_window);

  priv->focus_out = TRUE;
  g_signal_emit_by_name (toplevel, "move-focus", direction_type);
  priv->focus_out = FALSE;

  g_object_unref (scrolled_window);
}

static void
gtk_scrolled_window_relative_allocation (GtkWidget     *widget,
					 GtkAllocation *allocation)
{
  GtkAllocation widget_allocation;
  GtkScrolledWindow *scrolled_window;
  GtkScrolledWindowPrivate *priv;
  GtkStyle *style;
  gint sb_spacing;
  gint sb_width;
  gint sb_height;

  g_return_if_fail (widget != NULL);
  g_return_if_fail (allocation != NULL);

  scrolled_window = GTK_SCROLLED_WINDOW (widget);
  priv = scrolled_window->priv;

  /* Get possible scrollbar dimensions */
  sb_spacing = _gtk_scrolled_window_get_scrollbar_spacing (scrolled_window);
  gtk_widget_get_preferred_height (priv->hscrollbar, &sb_height, NULL);
  gtk_widget_get_preferred_width (priv->vscrollbar, &sb_width, NULL);

  /* Subtract some things from our available allocation size */
  allocation->x = 0;
  allocation->y = 0;

  if (priv->shadow_type != GTK_SHADOW_NONE)
    {
      style = gtk_widget_get_style (widget);
      allocation->x += style->xthickness;
      allocation->y += style->ythickness;
    }

  gtk_widget_get_allocation (widget, &widget_allocation);
  allocation->width = MAX (1, (gint) widget_allocation.width - allocation->x * 2);
  allocation->height = MAX (1, (gint) widget_allocation.height - allocation->y * 2);

  if (priv->vscrollbar_visible)
    {
      gboolean is_rtl;

      is_rtl = gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL;
  
      if ((!is_rtl && 
	   (priv->real_window_placement == GTK_CORNER_TOP_RIGHT ||
	    priv->real_window_placement == GTK_CORNER_BOTTOM_RIGHT)) ||
	  (is_rtl && 
	   (priv->real_window_placement == GTK_CORNER_TOP_LEFT ||
	    priv->real_window_placement == GTK_CORNER_BOTTOM_LEFT)))
	allocation->x += (sb_width +  sb_spacing);

      allocation->width = MAX (1, allocation->width - (sb_width + sb_spacing));
    }
  if (priv->hscrollbar_visible)
    {

      if (priv->real_window_placement == GTK_CORNER_BOTTOM_LEFT ||
	  priv->real_window_placement == GTK_CORNER_BOTTOM_RIGHT)
	allocation->y += (sb_height + sb_spacing);

      allocation->height = MAX (1, allocation->height - (sb_height + sb_spacing));
    }
}

static void
gtk_scrolled_window_size_allocate (GtkWidget     *widget,
				   GtkAllocation *allocation)
{
  GtkScrolledWindow *scrolled_window;
  GtkScrolledWindowPrivate *priv;
  GtkStyle *style;
  GtkBin *bin;
  GtkAllocation relative_allocation;
  GtkAllocation child_allocation;
  GtkWidget *child;
  gboolean scrollbars_within_bevel;
  gint sb_spacing;
  gint sb_width;
  gint sb_height;
 


  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (widget));
  g_return_if_fail (allocation != NULL);

  scrolled_window = GTK_SCROLLED_WINDOW (widget);
  bin = GTK_BIN (scrolled_window);
  priv = scrolled_window->priv;

  /* Get possible scrollbar dimensions */
  sb_spacing = _gtk_scrolled_window_get_scrollbar_spacing (scrolled_window);
  gtk_widget_get_preferred_height (priv->hscrollbar, &sb_height, NULL);
  gtk_widget_get_preferred_width (priv->vscrollbar, &sb_width, NULL);

  style = gtk_widget_get_style (widget);
  gtk_widget_style_get (widget, "scrollbars-within-bevel", &scrollbars_within_bevel, NULL);

  gtk_widget_set_allocation (widget, allocation);

  if (priv->hscrollbar_policy == GTK_POLICY_ALWAYS)
    priv->hscrollbar_visible = TRUE;
  else if (priv->hscrollbar_policy == GTK_POLICY_NEVER)
    priv->hscrollbar_visible = FALSE;
  if (priv->vscrollbar_policy == GTK_POLICY_ALWAYS)
    priv->vscrollbar_visible = TRUE;
  else if (priv->vscrollbar_policy == GTK_POLICY_NEVER)
    priv->vscrollbar_visible = FALSE;

  child = gtk_bin_get_child (bin);
  if (child && gtk_widget_get_visible (child))
    {
      gint child_min_width;
      gint child_min_height;
      gboolean previous_hvis;
      gboolean previous_vvis;
      guint count = 0;

      /* In the case that both scrollbars are visible in the previous round,
       * we dont do our guess-work before hand because it's possible some
       * infinite recursion was detected (leave it up to the child scrollable
       * widget in this case to drive the scrollbar visibility completely 
       * with the adjustment values).
       */
      if (!priv->vscrollbar_visible || !priv->hscrollbar_visible)
	{

	  /* Determine scrollbar visibility first via hfw apis */
	  if (gtk_widget_get_request_mode (child) == GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH)
	    {
	      gtk_widget_get_preferred_width (child, &child_min_width, NULL);
	      
	      if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
		{
		  /* First try without a vertical scrollbar if the content will fit the height
		   * given the extra width of the scrollbar */
		  gtk_widget_get_preferred_height_for_width (child, allocation->width, 
							     &child_min_height, NULL);
		  
		  if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
		    {
		      /* Does the content height fit the allocation height ? */
		      priv->vscrollbar_visible = child_min_height > allocation->height;
		      
		      /* Does the content width fit the allocation with minus a possible scrollbar ? */
		      priv->hscrollbar_visible = 
			child_min_width > allocation->width - 
			(priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
		      
		      /* Now that we've guessed the hscrollbar, does the content height fit
		       * the possible new allocation height ? */
		      priv->vscrollbar_visible = 
			child_min_height > allocation->height - 
			(priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
		      
		      /* Now that we've guessed the vscrollbar, does the content width fit
		       * the possible new allocation width ? */
		      priv->hscrollbar_visible = 
			child_min_width > allocation->width - 
			(priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
		    }
		  else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
		    {
		      priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
		      priv->vscrollbar_visible = child_min_height > allocation->height - 
			(priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
		    }
		}
	      else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
		{
		  priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
		  
		  if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
		    priv->hscrollbar_visible = 
		      child_min_width > allocation->width - 
		      (priv->vscrollbar_visible ? 0 : sb_width + sb_spacing);
		  else
		    priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
		}
	    } 
	  else /* GTK_SIZE_REQUEST_WIDTH_FOR_HEIGHT */
	    {
	      gtk_widget_get_preferred_height (child, &child_min_height, NULL);
	      
	      if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
		{
		  /* First try without a horizontal scrollbar if the content will fit the width
		   * given the extra height of the scrollbar */
		  gtk_widget_get_preferred_width_for_height (child, allocation->height, 
							     &child_min_width, NULL);
		  
		  if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
		    {
		      /* Does the content width fit the allocation width ? */
		      priv->hscrollbar_visible = child_min_width > allocation->width;
		      
		      /* Does the content height fit the allocation with minus a possible scrollbar ? */
		      priv->vscrollbar_visible = 
			child_min_height > allocation->height - 
			(priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
		      
		      /* Now that we've guessed the vscrollbar, does the content width fit
		       * the possible new allocation width ? */
		      priv->hscrollbar_visible = 
			child_min_width > allocation->width - 
			(priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
		      
		      /* Now that we've guessed the hscrollbar, does the content height fit
		       * the possible new allocation height ? */
		      priv->vscrollbar_visible = 
			child_min_height > allocation->height - 
			(priv->hscrollbar_visible ? sb_height + sb_spacing : 0);
		    }
		  else /* priv->vscrollbar_policy != GTK_POLICY_AUTOMATIC */
		    {
		      priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
		      priv->hscrollbar_visible = child_min_width > allocation->width - 
			(priv->vscrollbar_visible ? sb_width + sb_spacing : 0);
		    }
		}
	      else /* priv->hscrollbar_policy != GTK_POLICY_AUTOMATIC */
		{
		  priv->hscrollbar_visible = priv->hscrollbar_policy != GTK_POLICY_NEVER;
		  
		  if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
		    priv->vscrollbar_visible = 
		      child_min_height > allocation->height - 
		      (priv->hscrollbar_visible ? 0 : sb_height + sb_spacing);
		  else
		    priv->vscrollbar_visible = priv->vscrollbar_policy != GTK_POLICY_NEVER;
		}
	    }
	}

      /* Now after guessing scrollbar visibility; fall back on the allocation loop which 
       * observes the adjustments to detect scrollbar visibility and also avoids 
       * infinite recursion
       */
      do
	{
	  gtk_scrolled_window_relative_allocation (widget, &relative_allocation);
	  
	  child_allocation.x = relative_allocation.x + allocation->x;
	  child_allocation.y = relative_allocation.y + allocation->y;
	  child_allocation.width = relative_allocation.width;
	  child_allocation.height = relative_allocation.height;

	  previous_hvis = priv->hscrollbar_visible;
	  previous_vvis = priv->vscrollbar_visible;

	  gtk_widget_size_allocate (child, &child_allocation);

	  /* If, after the first iteration, the hscrollbar and the
	   * vscrollbar flip visiblity, then we need both.
	   */
	  if (count &&
	      previous_hvis != priv->hscrollbar_visible &&
	      previous_vvis != priv->vscrollbar_visible)
	    {
	      priv->hscrollbar_visible = TRUE;
	      priv->vscrollbar_visible = TRUE;

	      /* a new resize is already queued at this point,
	       * so we will immediatedly get reinvoked
	       */
	      return;
	    }
	  
	  count++;
	}
      while (previous_hvis != priv->hscrollbar_visible ||
	     previous_vvis != priv->vscrollbar_visible);
    }
  else
    {
      priv->hscrollbar_visible = priv->hscrollbar_policy == GTK_POLICY_ALWAYS;
      priv->vscrollbar_visible = priv->vscrollbar_policy == GTK_POLICY_ALWAYS;
      gtk_scrolled_window_relative_allocation (widget, &relative_allocation);
    }

  if (priv->hscrollbar_visible)
    {
      if (!gtk_widget_get_visible (priv->hscrollbar))
	gtk_widget_show (priv->hscrollbar);

      child_allocation.x = relative_allocation.x;
      if (priv->real_window_placement == GTK_CORNER_TOP_LEFT ||
	  priv->real_window_placement == GTK_CORNER_TOP_RIGHT)
	child_allocation.y = (relative_allocation.y +
			      relative_allocation.height +
			      sb_spacing +
			      (priv->shadow_type == GTK_SHADOW_NONE ?
			       0 : style->ythickness));
      else
	child_allocation.y = 0;

      child_allocation.width = relative_allocation.width;
      child_allocation.height = sb_height;
      child_allocation.x += allocation->x;
      child_allocation.y += allocation->y;

      if (priv->shadow_type != GTK_SHADOW_NONE)
	{
          if (!scrollbars_within_bevel)
            {
              child_allocation.x -= style->xthickness;
              child_allocation.width += 2 * style->xthickness;
            }
          else if (GTK_CORNER_TOP_RIGHT == priv->real_window_placement ||
                   GTK_CORNER_TOP_LEFT == priv->real_window_placement)
            {
              child_allocation.y -= style->ythickness;
            }
          else
            {
              child_allocation.y += style->ythickness;
            }
	}

      gtk_widget_size_allocate (priv->hscrollbar, &child_allocation);
    }
  else if (gtk_widget_get_visible (priv->hscrollbar))
    gtk_widget_hide (priv->hscrollbar);

  if (priv->vscrollbar_visible)
    {
      if (!gtk_widget_get_visible (priv->vscrollbar))
	gtk_widget_show (priv->vscrollbar);

      if ((gtk_widget_get_direction (widget) == GTK_TEXT_DIR_RTL && 
	   (priv->real_window_placement == GTK_CORNER_TOP_RIGHT ||
	    priv->real_window_placement == GTK_CORNER_BOTTOM_RIGHT)) ||
	  (gtk_widget_get_direction (widget) == GTK_TEXT_DIR_LTR && 
	   (priv->real_window_placement == GTK_CORNER_TOP_LEFT ||
	    priv->real_window_placement == GTK_CORNER_BOTTOM_LEFT)))
	child_allocation.x = (relative_allocation.x +
			      relative_allocation.width +
			      sb_spacing +
			      (priv->shadow_type == GTK_SHADOW_NONE ?
			       0 : style->xthickness));
      else
	child_allocation.x = 0;

      child_allocation.y = relative_allocation.y;
      child_allocation.width = sb_width;
      child_allocation.height = relative_allocation.height;
      child_allocation.x += allocation->x;
      child_allocation.y += allocation->y;

      if (priv->shadow_type != GTK_SHADOW_NONE)
	{
          if (!scrollbars_within_bevel)
            {
              child_allocation.y -= style->ythickness;
	      child_allocation.height += 2 * style->ythickness;
            }
          else if (GTK_CORNER_BOTTOM_LEFT == priv->real_window_placement ||
                   GTK_CORNER_TOP_LEFT == priv->real_window_placement)
            {
              child_allocation.x -= style->xthickness;
            }
          else
            {
              child_allocation.x += style->xthickness;
            }
	}

      gtk_widget_size_allocate (priv->vscrollbar, &child_allocation);
    }
  else if (gtk_widget_get_visible (priv->vscrollbar))
    gtk_widget_hide (priv->vscrollbar);
}

static gboolean
gtk_scrolled_window_scroll_event (GtkWidget      *widget,
				  GdkEventScroll *event)
{
  GtkScrolledWindowPrivate *priv;
  GtkScrolledWindow *scrolled_window;
  GtkWidget *range;

  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (widget), FALSE);
  g_return_val_if_fail (event != NULL, FALSE);  

  scrolled_window = GTK_SCROLLED_WINDOW (widget);
  priv = scrolled_window->priv;

  if (event->direction == GDK_SCROLL_UP || event->direction == GDK_SCROLL_DOWN)
    range = priv->vscrollbar;
  else
    range = priv->hscrollbar;

  if (range && gtk_widget_get_visible (range))
    {
      GtkAdjustment *adj = gtk_range_get_adjustment (GTK_RANGE (range));
      gdouble delta;

      delta = _gtk_range_get_wheel_delta (GTK_RANGE (range), event->direction);

      gtk_adjustment_set_value (adj, adj->value + delta);

      return TRUE;
    }

  return FALSE;
}

static gboolean
gtk_scrolled_window_focus (GtkWidget        *widget,
			   GtkDirectionType  direction)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkWidget *child;
  gboolean had_focus_child;

  had_focus_child = gtk_container_get_focus_child (GTK_CONTAINER (widget)) != NULL;

  if (priv->focus_out)
    {
      priv->focus_out = FALSE; /* Clear this to catch the wrap-around case */
      return FALSE;
    }
  
  if (gtk_widget_is_focus (widget))
    return FALSE;

  /* We only put the scrolled window itself in the focus chain if it
   * isn't possible to focus any children.
   */
  child = gtk_bin_get_child (GTK_BIN (widget));
  if (child)
    {
      if (gtk_widget_child_focus (child, direction))
	return TRUE;
    }

  if (!had_focus_child && gtk_widget_get_can_focus (widget))
    {
      gtk_widget_grab_focus (widget);
      return TRUE;
    }
  else
    return FALSE;
}

static void
gtk_scrolled_window_adjustment_changed (GtkAdjustment *adjustment,
					gpointer       data)
{
  GtkScrolledWindowPrivate *priv;;
  GtkScrolledWindow *scrolled_window;

  g_return_if_fail (adjustment != NULL);
  g_return_if_fail (data != NULL);

  scrolled_window = GTK_SCROLLED_WINDOW (data);
  priv = scrolled_window->priv;

  if (priv->hscrollbar &&
      adjustment == gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)))
    {
      if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC)
	{
	  gboolean visible;

	  visible = priv->hscrollbar_visible;
	  priv->hscrollbar_visible = (adjustment->upper - adjustment->lower >
					      adjustment->page_size);
	  if (priv->hscrollbar_visible != visible)
	    gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
	}
    }
  else if (priv->vscrollbar &&
	   adjustment == gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar)))
    {
      if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC)
	{
	  gboolean visible;

	  visible = priv->vscrollbar_visible;
	  priv->vscrollbar_visible = (adjustment->upper - adjustment->lower >
					      adjustment->page_size);
	  if (priv->vscrollbar_visible != visible)
	    gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
	}
    }
}

static void
gtk_scrolled_window_add (GtkContainer *container,
			 GtkWidget    *child)
{
  GtkScrolledWindowPrivate *priv;
  GtkScrolledWindow *scrolled_window;
  GtkBin *bin;
  GtkWidget *child_widget;

  bin = GTK_BIN (container);
  child_widget = gtk_bin_get_child (bin);
  g_return_if_fail (child_widget == NULL);

  scrolled_window = GTK_SCROLLED_WINDOW (container);
  priv = scrolled_window->priv;

  _gtk_bin_set_child (bin, child);
  gtk_widget_set_parent (child, GTK_WIDGET (bin));

  /* this is a temporary message */
  if (!gtk_widget_set_scroll_adjustments (child,
					  gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar)),
					  gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar))))
    g_warning ("gtk_scrolled_window_add(): cannot add non scrollable widget "
	       "use gtk_scrolled_window_add_with_viewport() instead");
}

static void
gtk_scrolled_window_remove (GtkContainer *container,
			    GtkWidget    *child)
{
  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (container));
  g_return_if_fail (child != NULL);
  g_return_if_fail (gtk_bin_get_child (GTK_BIN (container)) == child);
  
  gtk_widget_set_scroll_adjustments (child, NULL, NULL);

  /* chain parent class handler to remove child */
  GTK_CONTAINER_CLASS (gtk_scrolled_window_parent_class)->remove (container, child);
}

/**
 * gtk_scrolled_window_add_with_viewport:
 * @scrolled_window: a #GtkScrolledWindow
 * @child: the widget you want to scroll
 *
 * Used to add children without native scrolling capabilities. This
 * is simply a convenience function; it is equivalent to adding the
 * unscrollable child to a viewport, then adding the viewport to the
 * scrolled window. If a child has native scrolling, use
 * gtk_container_add() instead of this function.
 *
 * The viewport scrolls the child by moving its #GdkWindow, and takes
 * the size of the child to be the size of its toplevel #GdkWindow. 
 * This will be very wrong for most widgets that support native scrolling;
 * for example, if you add a widget such as #GtkTreeView with a viewport,
 * the whole widget will scroll, including the column headings. Thus, 
 * widgets with native scrolling support should not be used with the 
 * #GtkViewport proxy.
 *
 * A widget supports scrolling natively if the 
 * set_scroll_adjustments_signal field in #GtkWidgetClass is non-zero,
 * i.e. has been filled in with a valid signal identifier.
 */
void
gtk_scrolled_window_add_with_viewport (GtkScrolledWindow *scrolled_window,
				       GtkWidget         *child)
{
  GtkBin *bin;
  GtkWidget *viewport;
  GtkWidget *child_widget;

  g_return_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window));
  g_return_if_fail (GTK_IS_WIDGET (child));
  g_return_if_fail (gtk_widget_get_parent (child) == NULL);

  bin = GTK_BIN (scrolled_window);
  child_widget = gtk_bin_get_child (bin);

  if (child_widget)
    {
      g_return_if_fail (GTK_IS_VIEWPORT (child_widget));
      g_return_if_fail (gtk_bin_get_child (GTK_BIN (child_widget)) == NULL);

      viewport = child_widget;
    }
  else
    {
      viewport =
        gtk_viewport_new (gtk_scrolled_window_get_hadjustment (scrolled_window),
			  gtk_scrolled_window_get_vadjustment (scrolled_window));
      gtk_container_add (GTK_CONTAINER (scrolled_window), viewport);
    }

  gtk_widget_show (viewport);
  gtk_container_add (GTK_CONTAINER (viewport), child);
}

/*
 * _gtk_scrolled_window_get_spacing:
 * @scrolled_window: a scrolled window
 * 
 * Gets the spacing between the scrolled window's scrollbars and
 * the scrolled widget. Used by GtkCombo
 * 
 * Return value: the spacing, in pixels.
 */
gint
_gtk_scrolled_window_get_scrollbar_spacing (GtkScrolledWindow *scrolled_window)
{
  GtkScrolledWindowClass *class;
    
  g_return_val_if_fail (GTK_IS_SCROLLED_WINDOW (scrolled_window), 0);

  class = GTK_SCROLLED_WINDOW_GET_CLASS (scrolled_window);

  if (class->scrollbar_spacing >= 0)
    return class->scrollbar_spacing;
  else
    {
      gint scrollbar_spacing;
      
      gtk_widget_style_get (GTK_WIDGET (scrolled_window),
			    "scrollbar-spacing", &scrollbar_spacing,
			    NULL);

      return scrollbar_spacing;
    }
}


static void
gtk_scrolled_window_get_preferred_size (GtkWidget      *widget,
                                        GtkOrientation  orientation,
                                        gint           *minimum_size,
                                        gint           *natural_size)
{
  GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
  GtkScrolledWindowPrivate *priv = scrolled_window->priv;
  GtkBin *bin = GTK_BIN (scrolled_window);
  gint extra_width;
  gint extra_height;
  gint scrollbar_spacing;
  GtkRequisition hscrollbar_requisition;
  GtkRequisition vscrollbar_requisition;
  GtkRequisition minimum_req, natural_req;
  GtkStyle *style;
  GtkWidget *child;
  gint min_child_size, nat_child_size;

  scrollbar_spacing = _gtk_scrolled_window_get_scrollbar_spacing (scrolled_window);

  extra_width = 0;
  extra_height = 0;
  minimum_req.width = 0;
  minimum_req.height = 0;
  natural_req.width = 0;
  natural_req.height = 0;

  gtk_widget_get_preferred_size (priv->hscrollbar,
                                 &hscrollbar_requisition, NULL);
  gtk_widget_get_preferred_size (priv->vscrollbar,
                                 &vscrollbar_requisition, NULL);

  child = gtk_bin_get_child (bin);
  if (child && gtk_widget_get_visible (child))
    {
      if (orientation == GTK_ORIENTATION_HORIZONTAL)
	{
	  gtk_widget_get_preferred_width (child,
                                          &min_child_size,
                                          &nat_child_size);

	  if (priv->hscrollbar_policy == GTK_POLICY_NEVER)
	    {
	      minimum_req.width += min_child_size;
	      natural_req.width += nat_child_size;
	    }
	  else
	    {
	      /* Always ask for at least enough to fit the scrollbars */
	      minimum_req.width += vscrollbar_requisition.width;
	      natural_req.width += vscrollbar_requisition.width;
	    }
	}
      else /* GTK_ORIENTATION_VERTICAL */
	{
	  gtk_widget_get_preferred_height (child,
                                           &min_child_size,
                                           &nat_child_size);

	  if (priv->vscrollbar_policy == GTK_POLICY_NEVER)
	    {
	      minimum_req.height += min_child_size;
	      natural_req.height += nat_child_size;
	    }
	  else
	    {
	      /* Always ask for at least enough to fit the scrollbars */
	      minimum_req.height += hscrollbar_requisition.height;
	      natural_req.height += hscrollbar_requisition.height;
	    }
	}
    }

  if (priv->hscrollbar_policy == GTK_POLICY_AUTOMATIC ||
      priv->hscrollbar_policy == GTK_POLICY_ALWAYS)
    {
      minimum_req.width = MAX (minimum_req.width, hscrollbar_requisition.width);
      natural_req.width = MAX (natural_req.width, hscrollbar_requisition.width);
      if (!extra_height || priv->hscrollbar_policy == GTK_POLICY_ALWAYS)
	extra_height = scrollbar_spacing + hscrollbar_requisition.height;
    }

  if (priv->vscrollbar_policy == GTK_POLICY_AUTOMATIC ||
      priv->vscrollbar_policy == GTK_POLICY_ALWAYS)
    {
      minimum_req.height = MAX (minimum_req.height, vscrollbar_requisition.height);
      natural_req.height = MAX (natural_req.height, vscrollbar_requisition.height);
      if (!extra_height || priv->vscrollbar_policy == GTK_POLICY_ALWAYS)
	extra_width = scrollbar_spacing + vscrollbar_requisition.width;
    }

  minimum_req.width  += extra_width;
  minimum_req.height += extra_height;
  natural_req.width  += extra_width;
  natural_req.height += extra_height;

  if (priv->shadow_type != GTK_SHADOW_NONE)
    {
      style = gtk_widget_get_style (GTK_WIDGET (widget));
      minimum_req.width += 2 * style->xthickness;
      minimum_req.height += 2 * style->ythickness;
      natural_req.width += 2 * style->xthickness;
      natural_req.height += 2 * style->ythickness;
    }

  if (orientation == GTK_ORIENTATION_HORIZONTAL)
    {
      if (minimum_size)
	*minimum_size = minimum_req.width;
      if (natural_size)
	*natural_size = natural_req.width;
    }
  else
    {
      if (minimum_size)
	*minimum_size = minimum_req.height;
      if (natural_size)
	*natural_size = natural_req.height;
    }
}

static void     
gtk_scrolled_window_get_preferred_width (GtkWidget *widget,
                                         gint      *minimum_size,
                                         gint      *natural_size)
{
  gtk_scrolled_window_get_preferred_size (widget, GTK_ORIENTATION_HORIZONTAL, minimum_size, natural_size);
}

static void
gtk_scrolled_window_get_preferred_height (GtkWidget *widget,
                                          gint      *minimum_size,
                                          gint      *natural_size)
{  
  gtk_scrolled_window_get_preferred_size (widget, GTK_ORIENTATION_VERTICAL, minimum_size, natural_size);
}

static void
gtk_scrolled_window_get_preferred_height_for_width (GtkWidget *widget,
                                                    gint       width,
                                                    gint      *minimum_height,
                                                    gint      *natural_height)
{
  g_return_if_fail (GTK_IS_WIDGET (widget));

  GTK_WIDGET_GET_CLASS (widget)->get_preferred_height (widget, minimum_height, natural_height);
}

static void
gtk_scrolled_window_get_preferred_width_for_height (GtkWidget *widget,
                                                    gint       height,
                                                    gint      *minimum_width,
                                                    gint      *natural_width)
{
  g_return_if_fail (GTK_IS_WIDGET (widget));

  GTK_WIDGET_GET_CLASS (widget)->get_preferred_width (widget, minimum_width, natural_width);
}