////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2012-2022 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <QAction>
#include <QApplication>
#include <QHBoxLayout>
#include <QLabel>
#include <QScreen>
#include <QStyle>
#include <QToolBar>
#include <QMenuBar>
#include <QWindow>

#include "gui-preferences-dw.h"
#include "gui-preferences-global.h"
#include "gui-preferences-mw.h"
#include "gui-preferences-sc.h"
#include "gui-settings.h"
#include "gui-utils.h"
#include "main-window.h"
#include "octave-dock-widget.h"
#include "octave-qobject.h"

namespace octave
{
  label_dock_widget::label_dock_widget (QWidget *p, base_qobject& oct_qobj)
    : QDockWidget (p), m_octave_qobj (oct_qobj),
      m_default_float_button (nullptr), m_default_close_button (nullptr)
  {
    QStyle *st = style ();
    m_icon_size = 0.75*st->pixelMetric (QStyle::PM_SmallIconSize);

    // keep track of the original buttons on the default title bar,
    // the button further left is considered "float"
    QList<QAbstractButton *> buttonlist = findChildren<QAbstractButton *> ();
    if (buttonlist.size () == 2)
      {
        if (buttonlist.at (0)->x () < buttonlist.at (1)->x ())
          {
            m_default_float_button = buttonlist.at (0);
            m_default_close_button = buttonlist.at (1);
          }
        else
          {
            m_default_float_button = buttonlist.at (1);
            m_default_close_button = buttonlist.at (0);
          }
      }

    resource_manager& rmgr = m_octave_qobj.get_resource_manager ();

    // the custom (extra) title bar of the widget
    m_title_widget = new QWidget ();

    m_dock_action = new QAction
      (rmgr.icon ("widget-undock", true), "", this);
    m_dock_action->setToolTip (tr ("Undock widget"));
    m_dock_button = new QToolButton (m_title_widget);
    m_dock_button->setDefaultAction (m_dock_action);
    m_dock_button->setFocusPolicy (Qt::NoFocus);
    m_dock_button->setIconSize (QSize (m_icon_size, m_icon_size));

    m_close_action = new QAction
      (rmgr.icon ("widget-close", true), "", this);
    m_close_action->setToolTip (tr ("Close widget"));
    m_close_button = new QToolButton (m_title_widget);
    m_close_button->setDefaultAction (m_close_action);
    m_close_button->setFocusPolicy (Qt::NoFocus);
    m_close_button->setIconSize (QSize (m_icon_size, m_icon_size));

    QString css_button = QString ("QToolButton {background: transparent; border: 0px;}");
    m_dock_button->setStyleSheet (css_button);
    m_close_button->setStyleSheet (css_button);

    QHBoxLayout *h_layout = new QHBoxLayout ();
    h_layout->addStretch (100);
    h_layout->addWidget (m_dock_button);
    h_layout->addWidget (m_close_button);
    h_layout->setSpacing (10);
    h_layout->setContentsMargins (5, 2, 2, 2);

    m_title_widget->setLayout (h_layout);

    if (p && (p->objectName () == gui_obj_name_main_window))
      {
        // Only connect the when a parent (main window) is given
        // copy & paste handling
        connect (p, SIGNAL (copyClipboard_signal ()),
                 this, SLOT (copyClipboard ()));
        connect (p, SIGNAL (pasteClipboard_signal ()),
                 this, SLOT (pasteClipboard ()));
        connect (p, SIGNAL (selectAll_signal ()),
                 this, SLOT (selectAll ()));

        // undo handling
        connect (p, SIGNAL (undo_signal ()), this, SLOT (do_undo ()));
      }
  }

  // set the title in the dockwidgets title bar
  void
  label_dock_widget::set_title (const QString& title)
  {
    QHBoxLayout *h_layout
      = static_cast<QHBoxLayout *> (m_title_widget->layout ());
    QLabel *label = new QLabel (title, m_title_widget);
    label->setStyleSheet ("background-color: transparent;");
    h_layout->insertWidget (0, label);
    setTitleBarWidget (m_title_widget);
    setWindowTitle (title);
  }


  static QString
  qdockwidget_css (const QString& close_icon, const QString& close_tooltip,
                   const QString& float_icon, const QString& float_tooltip,
                   int icon_size, const QString& titlebar_foreground,
                   const QString& titlebar_background)
  {
    return QString ("QDockWidget\n"
                    "{\n"
                    "%6"
                    "  border: none;\n"
                    "  titlebar-close-icon: url(%1);\n"
                    "  titlebar-normal-icon: url(%2);\n"
                    "}\n"
                    "\n"
                    "QDockWidget::close-button, QDockWidget::float-button\n"
                    "{\n"
                    "  border: none;\n"
                    "  icon-size: %3px;\n"
                    "}\n"
                    "\n"
                    "QAbstractButton#qt_dockwidget_closebutton\n"
                    "{\n"
                    "  qproperty-toolTip: \"%4\";\n"
                    "}\n"
                    "\n"
                    "QAbstractButton#qt_dockwidget_floatbutton\n"
                    "{\n"
                    "  qproperty-toolTip: \"%5\";\n"
                    "}\n"
                    "\n"
                    "QDockWidget::title {\n"
                    "  text-align: left;\n"
                    "%7"
                    "  padding-left: 1px;\n"
                    "}\n"
                    "\n"
                    "QDockWidget::close-button\n"
                    "{\n"
                    "  right: %8px;\n"
                    "  top: 3px;\n"
                    "}\n"
                    "\n"
                    "QDockWidget::float-button\n"
                    "{\n"
                    "  right: %9px;\n"
                    "  top: 3px;\n"
                    "}\n"
                    ).arg (close_icon).arg (float_icon).arg (icon_size)
                     .arg (close_tooltip).arg (float_tooltip)
                     .arg (titlebar_foreground).arg (titlebar_background)
                     .arg ((icon_size*2)/3).arg((icon_size*7)/3);
  }

  octave_dock_widget::octave_dock_widget (const QString& obj_name, QWidget *p,
                                          base_qobject& oct_qobj)
    : label_dock_widget (p, oct_qobj), m_adopted (false),
      m_custom_style (false), m_focus_follows_mouse (false),
      m_recent_float_geom (), m_recent_dock_geom (),
      m_waiting_for_mouse_button_release (false)
  {
    setObjectName (obj_name);

    // FIXME: Can we avoid the cast here?
    m_main_window = dynamic_cast<main_window *> (p);

    m_predecessor_widget = nullptr;

    connect (this, &octave_dock_widget::topLevelChanged,
             this, &octave_dock_widget::toplevel_change);
    connect (this, &octave_dock_widget::visibilityChanged,
             this, &octave_dock_widget::handle_visibility);

    if (m_default_float_button != nullptr)
      {
        disconnect (m_default_float_button, 0, 0, 0);
        connect (m_default_float_button, &QAbstractButton::clicked,
                 this, &octave_dock_widget::make_window);
      }
    connect (this, &octave_dock_widget::queue_make_window,
             this, &octave_dock_widget::make_window, Qt::QueuedConnection);
    connect (this, &octave_dock_widget::queue_make_widget,
             this, [=] () { make_widget (); }, Qt::QueuedConnection);

    shortcut_manager& scmgr = m_octave_qobj.get_shortcut_manager ();
    scmgr.set_shortcut (m_dock_action, sc_dock_widget_dock);
    m_dock_action->setShortcutContext (Qt::WidgetWithChildrenShortcut);
    addAction (m_dock_action);
    connect (m_dock_action, &QAction::triggered,
             this, &octave_dock_widget::make_window);

    scmgr.set_shortcut (m_close_action, sc_dock_widget_close);
    m_close_action->setShortcutContext (Qt::WidgetWithChildrenShortcut);
    addAction (m_close_action);
    connect (m_close_action, &QAction::triggered,
             this, &octave_dock_widget::change_visibility);

    m_close_action->setToolTip (tr ("Hide widget"));

    setStyleSheet (qdockwidget_css (
      global_icon_paths.at (ICON_THEME_OCTAVE) + "widget-close.png",
      QString ("Close widget"),
      global_icon_paths.at (ICON_THEME_OCTAVE) + "widget-undock.png",
      QString ("Undock widget"),
      m_icon_size,
      QString (""),
      QString ("")));

    if (widget ())
      widget ()->setToolTip (QString (""));

    m_icon_color = "";
    m_title_3d = 50;

    installEventFilter (this);

    setFocusPolicy (Qt::StrongFocus);

    setFeatures (QDockWidget::DockWidgetClosable
                 | QDockWidget::DockWidgetMovable
                 | QDockWidget::DockWidgetFloatable);

    handle_settings ();
  }

  void
  octave_dock_widget::init_window_menu_entry (void)
  {
    emit active_changed (isVisible ());  // emit once for init of window menu
  }

  // make the widget floating
  void
  octave_dock_widget::make_window (bool widget_was_dragged)
  {
    bool vis = isVisible ();

    // prevent follow-up calls by clearing state variable
    m_waiting_for_mouse_button_release = false;

    set_focus_predecessor ();  // set focus previously active widget if tabbed

    // Before unparenting, get current geometry for restoring if dragged
    QRect geom = geometry ();

    // the widget has to be reparented (parent = 0), preferably
    // from a non-toplevel widget otherwise may not have full
    // decorations, e.g., no taskbar icon and always in front
    if (isFloating ())
      setFloating (false);

    if (m_main_window)
      {
        // Before making it a separate (no more parent) floating widget,
        // remove the dock widget from the main window. This ensures
        // that tabbed widgets keep their focus when it is re-docked
        // later
        m_main_window->removeDockWidget (this);
      }

    setParent (0, Qt::CustomizeWindowHint | Qt::WindowTitleHint |
               Qt::WindowMinMaxButtonsHint | Qt::WindowCloseButtonHint | Qt::Window);

    // restore the last geometry when floating only if we have not dragged
    // the window outside the main window
    if (! widget_was_dragged)
      geom = m_recent_float_geom.isNull () ? QRect (50,100,480,480)
                                           : m_recent_float_geom;
    setGeometry (geom);

    // adjust the (un)dock action
    disconnect (m_dock_action, 0, this, 0);
    connect (m_dock_action, &QAction::triggered,
             this, &octave_dock_widget::make_widget);

    // adjust the (un)dock icon
    if (titleBarWidget ())
      {
        resource_manager& rmgr = m_octave_qobj.get_resource_manager ();
        m_dock_action->setIcon (rmgr.icon ("widget-dock" + m_icon_color, true));
        m_dock_action->setToolTip (tr ("Dock widget"));
      }
    else
      {
        disconnect (m_default_float_button, 0, this, 0);
        connect (m_default_float_button, &QAbstractButton::clicked,
                 this, &octave_dock_widget::make_widget);
      }

    raise ();
    activateWindow ();

    if (vis)
      {
        show ();
        setFocus ();
        set_style (true);
      }

    emit topLevelChanged (true);  // Be sure signal is emitted
  }

  // dock the widget
  void
  octave_dock_widget::make_widget (bool)
  {
    bool vis = isVisible ();

    // Since floating widget has no parent, we have to read it

    if (m_main_window)
      {
        gui_settings settings;

        settings.setValue (mw_state.key, m_main_window->saveState ());

        // Stay window, otherwise will bounce back to window by default
        // because there is no layout information for this widget in the
        // saved settings.
        setParent (m_main_window, Qt::Window);
        m_main_window->addDockWidget (Qt::BottomDockWidgetArea, this);
        m_adopted = false;
        // recover old window states, hide and re-show new added widget
        m_main_window->restoreState (settings.value (mw_state.key).toByteArray ());
        setFloating (false);
        // restore size using setGeometry instead of restoreGeometry
        // following this post:
        // https://forum.qt.io/topic/79326/qdockwidget-restoregeometry-not-working-correctly-when-qmainwindow-is-maximized/5
        setGeometry (m_recent_dock_geom);
      }

    // adjust the (un)dock icon
    disconnect (m_dock_action, 0, this, 0);
    connect (m_dock_action, &QAction::triggered,
             this, &octave_dock_widget::make_window);
    if (titleBarWidget ())
      {
        resource_manager& rmgr = m_octave_qobj.get_resource_manager ();

        m_dock_action->setIcon (rmgr.icon ("widget-undock" + m_icon_color, true));
        m_dock_action->setToolTip (tr ("Undock widget"));
      }
    else
      {
        disconnect (m_default_float_button, 0, this, 0);
        connect (m_default_float_button, &QAbstractButton::clicked,
                 this, &octave_dock_widget::make_window);
      }

    raise ();
    QApplication::setActiveWindow (this);

    if (vis)
      {
        show ();
        setFocus ();
        set_style (true);
      }
  }

  // dock the widget
  void
  octave_dock_widget::default_dock (bool)
  {
    setFloating (false);
  }

  // set the widget which previously had focus when tabified
  void
  octave_dock_widget::set_predecessor_widget (octave_dock_widget *prev_widget)
  {
    m_predecessor_widget = prev_widget;
  }

  void
  octave_dock_widget::set_main_window (main_window *mw)
  {
    m_main_window = mw;

    if (m_main_window)
      {
        connect (m_main_window, &main_window::copyClipboard_signal,
                 this, &octave_dock_widget::copyClipboard);

        connect (m_main_window, &main_window::pasteClipboard_signal,
                 this, &octave_dock_widget::pasteClipboard);

        connect (m_main_window, &main_window::selectAll_signal,
                 this, &octave_dock_widget::selectAll);

        connect (m_main_window, &main_window::undo_signal,
                 this, &octave_dock_widget::do_undo);
      }
  }

  // close event
  void
  octave_dock_widget::closeEvent (QCloseEvent *e)
  {
    emit active_changed (false);
    set_focus_predecessor ();
    save_settings ();

    QDockWidget::closeEvent (e);
  }

  // get focus widget
  QWidget *
  octave_dock_widget::focusWidget (void)
  {
    QWidget *w = QApplication::focusWidget ();
    if (w && w->focusProxy ()) w = w->focusProxy ();
    return w;
  }

  bool
  octave_dock_widget::event (QEvent *event)
  {
    // low-level check of whether docked-widget became a window via
    // double-click or via drag-and-drop
    if ( (event->type () == QEvent::MouseButtonDblClick && ! isFloating ())
         || (event->type () == QEvent::ActivationChange
             && m_waiting_for_mouse_button_release))
      {
        bool retval = QDockWidget::event (event);
        if (isFloating () && parent () != 0)
          {
            m_waiting_for_mouse_button_release = false;
            emit queue_make_window (event->type () != QEvent::MouseButtonDblClick);
          }
        return retval;
      }

    return QDockWidget::event (event);
  }

  void
  octave_dock_widget::handle_settings (void)
  {
    gui_settings settings;

    m_focus_follows_mouse = settings.value (dw_focus_follows_mouse).toBool ();

    m_custom_style
      = settings.value (dw_title_custom_style).toBool ();

    m_title_3d = settings.value (dw_title_3d.key, dw_title_3d.def).toInt ();

    m_fg_color
      = settings.value (dw_title_fg_color).value<QColor> ();

    m_fg_color_active
      = settings.value (dw_title_fg_color_active).value<QColor> ();

    m_bg_color = settings.value (dw_title_bg_color).value<QColor> ();

    m_bg_color_active
      = settings.value (dw_title_bg_color_active).value<QColor> ();

    QColor bcol (m_bg_color);
    QColor bcola (m_bg_color_active);

    if (! m_custom_style)
      {
        bcol = QWidget::palette ().color (m_title_widget->backgroundRole ());
        bcola = bcol;
      }

    int r, g, b;
    bcol.getRgb (&r, &g, &b);
    if (r+g+b < 400)
      m_icon_color = "-light";
    else
      m_icon_color = "";

    bcola.getRgb (&r, &g, &b);
    if (r+g+b < 400)
      m_icon_color_active = "-light";
    else
      m_icon_color_active = "";


    int x, y, w, h;
    QGuiApplication::primaryScreen ()->availableGeometry ().getRect (&x, &y, &w, &h);
    QRect default_floating_size = QRect (x+16, y+32, w/3, h/2);

    QRect default_dock_size;
    if (m_main_window)
      {
        // We have a main window, dock size depends on size of main window
        m_main_window->geometry ().getRect (&x, &y, &w, &h);
        default_dock_size = QRect (x+16, y+32, w/3, h/3);
      }
    else
      {
        // No main window, default dock size should never be used
        default_dock_size = QRect (0, 0, w/10, h/10);
      }

    m_recent_float_geom
      = settings.value (dw_float_geometry.key.arg (objectName ()),
                         default_floating_size).toRect ();

    adjust_to_screen (m_recent_float_geom, default_floating_size);

    // The following is required for ensure smooth transition from old
    // saveGeomety to new QRect setting (see comment for restoring size
    // of docked widgets)
    QVariant dock_geom
      = settings.value (dw_dock_geometry.key.arg (objectName ()),
                        default_dock_size);
    if (dock_geom.canConvert (QMetaType::QRect))
      m_recent_dock_geom = dock_geom.toRect ();
    else
      m_recent_dock_geom = dw_dock_geometry.def.toRect ();

    notice_settings ();  // call individual handler

    set_style (false);

    // Compacter design
    QToolBar *toolbar = findChild <QToolBar *> ();
    if (toolbar)
      toolbar->setStyleSheet (toolbar->styleSheet () + global_toolbar_style);

    QMenuBar *menubar = findChild <QMenuBar *> ();
    if (menubar)
      menubar->setStyleSheet (menubar->styleSheet () + global_menubar_style);

  }

  void
  octave_dock_widget::handle_active_dock_changed (octave_dock_widget *w_old,
                                                  octave_dock_widget *w_new)
  {
    if (m_custom_style && this == w_old)
      {
        set_style (false);
        update ();
      }

    if (m_custom_style && this == w_new)
      {
        set_style (true);
        update ();
      }
  }

  void
  octave_dock_widget::save_settings (void)
  {
    // save state of this dock-widget
    QString name = objectName ();

    gui_settings settings;

    store_geometry ();

    // conditional needed?
    if (! m_recent_float_geom.isNull ())
      settings.setValue (dw_float_geometry.key.arg (name), m_recent_float_geom);

    if (! m_recent_dock_geom.isEmpty ())
      settings.setValue (dw_dock_geometry.key.arg (name), m_recent_dock_geom);
    settings.setValue (dw_is_visible.key.arg (name), isVisible ()); // store visibility
    settings.setValue (dw_is_floating.key.arg (name), isFloating ()); // store floating
    settings.setValue (dw_is_minimized.key.arg (name), isMinimized ()); // store minimized

    settings.sync ();
  }

  bool octave_dock_widget::eventFilter (QObject *obj, QEvent *e)
  {
    // Ignore double clicks into window decoration elements
    if (e->type () == QEvent::NonClientAreaMouseButtonDblClick)
      {
        e->ignore ();
        return true;
      }

    // Detect mouse enter events if "focus follows mouse" is desired
    // for widgets docked to the main window (non floating) and activate
    // the widget currently under the mouse
    if (m_focus_follows_mouse && ! isFloating () && (e->type () == QEvent::Enter))
      setFocus ();

    return QDockWidget::eventFilter (obj, e);
  }

  void
  octave_dock_widget::store_geometry (void)
  {
    if (isFloating ())
      {
        if (! parent ())
          m_recent_float_geom = geometry ();
      }
    else
      {
        m_recent_dock_geom = geometry ();
      }
  }

  void
  octave_dock_widget::moveEvent (QMoveEvent *event)
  {
    store_geometry ();

    QDockWidget::moveEvent (event);
  }

  void
  octave_dock_widget::resizeEvent (QResizeEvent *event)
  {
    store_geometry ();

    QDockWidget::resizeEvent (event);
  }

  // slot for hiding the widget
  void
  octave_dock_widget::change_visibility (bool)
  {
    setVisible (false);
    emit active_changed (false);
  }

  void octave_dock_widget::activate (void)
  {
    if (! isVisible ())
      setVisible (true);

    setFocus ();
    activateWindow ();
    raise ();
  }

  void octave_dock_widget::handle_visibility (bool visible)
  {
    if (visible)
      {
        emit active_changed (true);
        if (! isFloating ())
          setFocus ();
      }
  }

  void
  octave_dock_widget::toplevel_change (bool toplevel)
  {
    QObject *dockobj;
    const char *docksig;

    if (titleBarWidget ())
      {
        dockobj = m_dock_action;
        docksig = SIGNAL (triggered (bool));
      }
    else
      {
        dockobj = m_default_float_button;
        docksig = SIGNAL (clicked (bool));
      }

    if (toplevel)
      {
        // This is a fallback in case the attempt to create a floated
        // top-level window fails and the QDockWidget remains a child
        // of the QMainWindow.
        connect (dockobj, docksig, this, SLOT (default_dock (bool)));

        // Could be dragging window, so must wait until there is a
        // change in focus.
        if (parent () != 0)
          m_waiting_for_mouse_button_release = true;
      }
    else
      {
        // If a drag-and-drop within the QMainWindow occurred, want to remain a widget.
        m_waiting_for_mouse_button_release = false;

        // Making into a widget immediately will mangle the double-click
        // status and cause problems on followup button clicks.
        if (parent () == 0)
          emit queue_make_widget ();
      }
  }

  void
  octave_dock_widget::set_style (bool active)
  {
    QString css_foreground;
    QString css_background;
    QString css_button;
    QString dock_icon;

    QString icon_col = m_icon_color;

    QString close_tooltip = "Close widget";
    QString dock_tooltip;

    if (isFloating ())
      {
        dock_icon = "widget-dock";
        dock_tooltip = "Dock widget";
      }
    else
      {
        dock_icon = "widget-undock";
        dock_tooltip = "Undock widget";
      }

#if defined (Q_OS_MAC)
    QString alignment = "center";
#else
    QString alignment = "center left";
#endif
    if (m_custom_style)
      {

        QColor bg_col, fg_col;

        if (active)
          {
            bg_col = m_bg_color_active;
            fg_col = m_fg_color_active;
            icon_col = m_icon_color_active;
          }
        else
          {
            bg_col = m_bg_color;
            fg_col = m_fg_color;
            icon_col = m_icon_color;
          }

        QColor bg_col_top, bg_col_bottom;
        if (m_title_3d > 0)
          {
            bg_col_top = bg_col.lighter (100 + m_title_3d);
            bg_col_bottom = bg_col.darker (100 + m_title_3d);
          }
        else
          {
            bg_col_top = bg_col.darker (100 - m_title_3d);
            bg_col_bottom = bg_col.lighter (100 - m_title_3d);
          }

        css_foreground = QString ("  color: %1;\n").arg (fg_col.name ());

        css_background =
          QString ("  background: qlineargradient(x1: 0, y1: 0, x2: 0, y2: 1,"
                   " stop: 0 %1, stop: 0.60 %2, stop: 0.95 %2 stop: 1.0 %3);\n").
          arg (bg_col_top.name ()).
          arg (bg_col.name ()).
          arg (bg_col_bottom.name ());
      }
    else
      {
        css_foreground = QString ("");
        css_background = QString ("");
      }

    QString full_dock_icon = dock_icon + icon_col;
    QString full_close_icon = "widget-close" + icon_col;
    if (titleBarWidget ())
      {
        resource_manager& rmgr = m_octave_qobj.get_resource_manager ();
        titleBarWidget ()->setStyleSheet (css_foreground + css_background);
        css_button = QString ("QToolButton {background: transparent; border: 0px;}");
        m_dock_button->setStyleSheet (css_button);
        m_close_button->setStyleSheet (css_button);
        m_dock_action->setIcon (rmgr.icon (full_dock_icon, true));
        m_close_action->setIcon (rmgr.icon (full_close_icon, true));
      }
    else
      {
        setStyleSheet (qdockwidget_css (global_icon_paths.at (ICON_THEME_OCTAVE) + full_close_icon + ".png",
                                        close_tooltip,
                                        global_icon_paths.at (ICON_THEME_OCTAVE) + full_dock_icon + ".png",
                                        dock_tooltip,
                                        m_icon_size,
                                        css_foreground,
                                        css_background));
      }
  }

  // set focus to previously active widget in tabbed widget stack
  void
  octave_dock_widget::set_focus_predecessor (void)
  {
    // only != 0 if widget was tabbed
    if (m_predecessor_widget && m_predecessor_widget->isVisible ())
      m_predecessor_widget->setFocus ();

    m_predecessor_widget = nullptr;

    // FIXME: Until cset bda0c5b38bda, the wrong keys "Dockwidget/..." were used
    // here.  This had no effect in Qt4, but does in Qt5.  In the following, the
    // four incorrect keys are updated if still present in the settings files.
    // The keys are also used in the settings dialog, but
    // octave_dock_widget::handle_settings is already called at program start.
    // These tests can be removed in a future version of Octave (version 6).

    resource_manager& rmgr = m_octave_qobj.get_resource_manager ();

    rmgr.update_settings_key ("Dockwidgets/title_bg_color",
                              dw_title_bg_color.key);

    rmgr.update_settings_key ("Dockwidgets/title_bg_color_active",
                              dw_title_bg_color_active.key);

    rmgr.update_settings_key ("Dockwidgets/title_fg_color",
                              dw_title_fg_color.key);

    rmgr.update_settings_key ("Dockwidgets/title_fg_color_active",
                              dw_title_fg_color_active.key);
  }
}