rawTherapee/rtgui/guiutils.h

/*
 *  This file is part of RawTherapee.
 *
 *  Copyright (c) 2004-2010 Gabor Horvath <hgabor@rawtherapee.com>
 *
 *  RawTherapee 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.
 *
 *  RawTherapee 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 RawTherapee.  If not, see <https://www.gnu.org/licenses/>.
 */
#pragma once

#include <functional>
#include <map>
#include <type_traits>

#include <gtkmm.h>

#include <cairomm/cairomm.h>

#include "threadutils.h"

#include "rtengine/coord.h"
#include "rtengine/noncopyable.h"

namespace rtengine
{

namespace procparams
{

class ProcParams;

struct CropParams;

}

}

class RTImage;

Glib::ustring escapeHtmlChars(const Glib::ustring &src);
bool removeIfThere (Gtk::Container* cont, Gtk::Widget* w, bool increference = true);
bool confirmOverwrite (Gtk::Window& parent, const std::string& filename);
void writeFailed (Gtk::Window& parent, const std::string& filename);
void drawCrop (Cairo::RefPtr<Cairo::Context> cr, int imx, int imy, int imw, int imh, int startx, int starty, double scale, const rtengine::procparams::CropParams& cparams, bool drawGuide = true, bool useBgColor = true, bool fullImageVisible = true);
gboolean acquireGUI(void* data);
void setExpandAlignProperties(Gtk::Widget *widget, bool hExpand, bool vExpand, enum Gtk::Align hAlign, enum Gtk::Align vAlign);
Gtk::Border getPadding(const Glib::RefPtr<Gtk::StyleContext> style);

class IdleRegister final :
    public rtengine::NonCopyable
{
public:
    ~IdleRegister();

    void add(std::function<bool ()> function, gint priority = G_PRIORITY_DEFAULT_IDLE);
    void destroy();

private:
    struct DataWrapper {
        IdleRegister* const self;
        std::function<bool ()> function;
    };

    std::map<const DataWrapper*, guint> ids;
    MyMutex mutex;
};

struct ScopedEnumHash {
    template<typename T, typename std::enable_if<std::is_enum<T>::value && !std::is_convertible<T, int>::value, int>::type = 0>
    size_t operator ()(T val) const noexcept
    {
        using type = typename std::underlying_type<T>::type;

        return std::hash<type>{}(static_cast<type>(val));
    }
};


// TODO: The documentation says gdk_threads_enter and gdk_threads_leave should be replaced
// by g_main_context_invoke(), g_idle_add() and related functions, but this will require more extensive changes.
// We silence those warnings until then so that we notice the others.
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-declarations"

/**
 * @brief Lock GTK for critical section.
 *
 * Will unlock on destruction. To use:
 *
 *   <code>
 *     {
 *       GThreadLock lock;
 *       // critical code
 *     }
 *   </code>
 */
class GThreadLock final
{
public:
    GThreadLock()
    {
        gdk_threads_enter();
    }
    ~GThreadLock()
    {
        gdk_threads_leave();
    }
};

/**
 * @brief Unlock GTK critical section.
 *
 * Will relock on destruction.
 */
class GThreadUnLock final
{
public:
    GThreadUnLock()
    {
        gdk_threads_leave();
    }
    ~GThreadUnLock()
    {
        gdk_threads_enter();
    }
};

#pragma GCC diagnostic pop

class ConnectionBlocker final
{
public:
    explicit ConnectionBlocker (Gtk::Widget *associatedWidget, sigc::connection& connection) : connection (associatedWidget ? &connection : nullptr), wasBlocked(false)
    {
        if (this->connection) {
            wasBlocked = connection.block();
        }
    }
    explicit ConnectionBlocker (sigc::connection& connection) : connection (&connection)
    {
            wasBlocked = connection.block();
    }
    ~ConnectionBlocker ()
    {
        if (connection) {
            connection->block(wasBlocked);
        }
    }
private:
    sigc::connection *connection;
    bool wasBlocked;
};

/**
 * @brief Glue box to control visibility of the MyExpender's content ; also handle the frame around it
 */
class ExpanderBox final : public Gtk::EventBox
{
private:
    Gtk::Container *pC;

public:
    explicit ExpanderBox( Gtk::Container *p);
    ~ExpanderBox( ) override
    {
        delete pC;
    }

    void setLevel(int level);

    void show() {}
    void show_all();
    void hide() {}
    void set_visible(bool isVisible = true) {}

    void showBox();
    void hideBox();

//  bool on_draw(const ::Cairo::RefPtr< Cairo::Context> &cr);
};

/**
 * @brief A custom Expander class, that can handle widgets in the title bar
 *
 * Custom made expander for responsive widgets in the header. It also handle a "enabled/disabled" property that display
 * a different arrow depending on this boolean value.
 *
 * Warning: once you've instantiated this class with a text label or a widget label, you won't be able to revert to the other solution.
 */
class MyExpander final : public Gtk::Box
{
public:
    typedef sigc::signal<void> type_signal_enabled_toggled;
private:
    type_signal_enabled_toggled message;
    const Glib::ustring inconsistentImage; /// "inconsistent" image, displayed when useEnabled is true ; in this case, nothing will tell that an expander is opened/closed
    const Glib::ustring enabledImage;      ///      "enabled" image, displayed when useEnabled is true ; in this case, nothing will tell that an expander is opened/closed
    const Glib::ustring disabledImage;     ///     "disabled" image, displayed when useEnabled is true ; in this case, nothing will tell that an expander is opened/closed
    const Glib::ustring openedImage;       ///       "opened" image, displayed when useEnabled is false
    const Glib::ustring closedImage;       ///       "closed" image, displayed when useEnabled is false
    bool enabled;               /// Enabled feature (default to true)
    bool inconsistent;          /// True if the enabled button is inconsistent
    Gtk::EventBox *titleEvBox;  /// EventBox of the title, to get a connector from it
    Gtk::Box *headerHBox;
    bool flushEvent;            /// Flag to control the weird event mechanism of Gtk (please prove me wrong!)
    ExpanderBox* expBox;        /// Frame that includes the child and control its visibility
    Gtk::EventBox *imageEvBox;  /// Enable/Disable or Open/Close arrow event box

    using Gtk::Container::add;

    /// Triggered on opened/closed event
    bool on_toggle(GdkEventButton* event);
    /// Triggered on enabled/disabled change -> will emit a toggle event to the connected objects
    bool on_enabled_change(GdkEventButton* event);
    /// Used to handle the colored background for the whole Title
    bool on_enter_leave_title (GdkEventCrossing* event);
    /// Used to handle the colored background for the Enable button
    bool on_enter_leave_enable (GdkEventCrossing* event);

    void updateStyle();

protected:
    Gtk::Container* child;      /// Gtk::Contained to display below the expander's title
    Gtk::Widget* headerWidget;  /// Widget to display in the header, next to the arrow image ; can be NULL if the "string" version of the ctor has been used
    RTImage* statusImage;       /// Image to display the opened/closed status (if useEnabled is false) of the enabled/disabled status (if useEnabled is true)
    Gtk::Label* label;          /// Text to display in the header, next to the arrow image ; can be NULL if the "widget" version of the ctor has been used
    bool useEnabled;            /// Set whether to handle an enabled/disabled feature and display the appropriate images

public:

    /** @brief Create a custom expander with a simple header made of a label.
     * @param useEnabled Set whether to handle an enabled/disabled toggle button and display the appropriate image
     * @param titleLabel A string to display in the header. Warning: you won't be able to switch to a widget label.
     */
    MyExpander(bool useEnabled, Glib::ustring titleLabel);

    /** Create a custom expander with a custom - and responsive - widget
     * @param useEnabled Set whether to handle an enabled/disabled toggle button and display the appropriate image
     * @param titleWidget A widget to display in the header. Warning: you won't be able to switch to a string label.
     */
    MyExpander(bool useEnabled, Gtk::Widget* titleWidget);

    Glib::SignalProxy1< bool, GdkEventButton* > signal_button_release_event()
    {
        return titleEvBox->signal_button_release_event();
    };
    type_signal_enabled_toggled signal_enabled_toggled();

    /// Set the nesting level of the Expander to adapt its style accordingly
    void setLevel(int level);

    /// Set a new label string. If it has been instantiated with a Gtk::Widget, this method will do nothing
    void setLabel (Glib::ustring newLabel);
    /// Set a new label string. If it has been instantiated with a Gtk::Widget, this method will do nothing
    void setLabel (Gtk::Widget *newWidget);

    /// Get whether the enabled option is set (to true or false) or unset (i.e. undefined)
    bool get_inconsistent();
    /// Set whether the enabled option is set (to true or false) or unset (i.e. undefined)
    void set_inconsistent(bool isInconsistent);

    /// Get whether the enabled button is used or not
    bool getUseEnabled();
    /// Get whether the enabled button is on or off
    bool getEnabled();
    /// If not inconsistent, set the enabled button to true or false and emit the message if the state is different
    /// If inconsistent, set the internal value to true or false, but do not update the image and do not emit the message
    void setEnabled(bool isEnabled);
    /// Adds a Tooltip to the Enabled button, if it exist ; do nothing otherwise
    void setEnabledTooltipMarkup(Glib::ustring tooltipMarkup);
    void setEnabledTooltipText(Glib::ustring tooltipText);

    /// Get the header widget. It'll send back the Gtk::Label* if it has been instantiated with a simple text
    Gtk::Widget* getLabelWidget() const
    {
        return headerWidget ? headerWidget : label;
    }

    /// Set the collapsed/expanded state of the expander
    void set_expanded( bool expanded );

    /// Get the collapsed/expanded state of the expander
    bool get_expanded();

    /// Add a Gtk::Container for the content of the expander
    /// Warning: do not manually Show/Hide the widget, because this parameter is handled by the click on the Expander's title
    void add  (Gtk::Container& widget, bool setChild = true);

    void updateVScrollbars(bool hide);
};


/**
 * @brief subclass of Gtk::ScrolledWindow in order to handle the scrollwheel
 */
class MyScrolledWindow final : public Gtk::ScrolledWindow
{

    bool on_scroll_event (GdkEventScroll* event) override;
    void get_preferred_width_vfunc (int& minimum_width, int& natural_width) const override;
    void get_preferred_height_vfunc (int& minimum_height, int& natural_height) const override;
    void get_preferred_height_for_width_vfunc (int width, int &minimum_height, int &natural_height) const override;

public:
    MyScrolledWindow();
};

/**
 * @brief subclass of Gtk::ScrolledWindow in order to handle the large toolbars (wider than available space)
 */
class MyScrolledToolbar final : public Gtk::ScrolledWindow
{

    bool on_scroll_event (GdkEventScroll* event) override;
    void get_preferred_height_vfunc (int& minimum_height, int& natural_height) const override;

public:
    MyScrolledToolbar();
};

/**
 * @brief subclass of Gtk::ComboBox in order to handle the scrollwheel
 */
class MyComboBox : public Gtk::ComboBox
{
    int naturalWidth, minimumWidth;

    bool on_scroll_event (GdkEventScroll* event) override;
    void get_preferred_width_vfunc (int &minimum_width, int &natural_width) const override;
    void get_preferred_width_for_height_vfunc (int height, int &minimum_width, int &natural_width) const override;

public:
    MyComboBox ();

    void setPreferredWidth (int minimum_width, int natural_width);
};

/**
 * @brief subclass of Gtk::ComboBoxText in order to handle the scrollwheel
 */
class MyComboBoxText final : public Gtk::ComboBoxText
{
    int naturalWidth, minimumWidth;
    sigc::connection myConnection;

    bool on_scroll_event (GdkEventScroll* event) override;
    void get_preferred_width_vfunc (int &minimum_width, int &natural_width) const override;
    void get_preferred_width_for_height_vfunc (int height, int &minimum_width, int &natural_width) const override;

public:
    explicit MyComboBoxText (bool has_entry = false);

    void setPreferredWidth (int minimum_width, int natural_width);
    void connect(const sigc::connection &connection) { myConnection = connection; }
    void block(bool blocked) { myConnection.block(blocked); }
};

/**
 * @brief subclass of Gtk::SpinButton in order to handle the scrollwheel
 */
class MySpinButton final : public Gtk::SpinButton
{

protected:
    bool on_scroll_event (GdkEventScroll* event) override;
    bool on_key_press_event (GdkEventKey* event) override;

public:
    MySpinButton ();
    void updateSize();
};

/**
 * @brief subclass of Gtk::Scale in order to handle the scrollwheel
 */
class MyHScale final : public Gtk::Scale
{

protected:
    bool on_scroll_event (GdkEventScroll* event) override;
    bool on_key_press_event (GdkEventKey* event) override;

};

class MyFileChooserWidget
{
public:
    virtual ~MyFileChooserWidget() = default;

    sigc::signal<void> &signal_selection_changed();
    sigc::signal<void> &signal_file_set();

    std::string get_filename() const;
    bool set_filename(const std::string &filename);

    void add_filter(const Glib::RefPtr<Gtk::FileFilter> &filter);
    void remove_filter(const Glib::RefPtr<Gtk::FileFilter> &filter);
    void set_filter(const Glib::RefPtr<Gtk::FileFilter> &filter);
    std::vector<Glib::RefPtr<Gtk::FileFilter>> list_filters() const;

    bool set_current_folder(const std::string &filename);
    std::string get_current_folder() const;

    bool add_shortcut_folder(const std::string &folder);
    bool remove_shortcut_folder(const std::string &folder);

    void unselect_all();
    void unselect_filename(const std::string &filename);

    void set_show_hidden(bool yes);

protected:
    explicit MyFileChooserWidget(const Glib::ustring &title, Gtk::FileChooserAction action=Gtk::FILE_CHOOSER_ACTION_OPEN);

    static std::unique_ptr<Gtk::Image> make_folder_image();

    void show_chooser(Gtk::Widget *parent);
    virtual void on_filename_set();

private:
    class Impl;

    std::unique_ptr<Impl> pimpl;
};

/**
 * @brief subclass of Gtk::FileChooserButton in order to handle the scrollwheel
 */
class MyFileChooserButton final : public Gtk::Button, public MyFileChooserWidget
{
private:
    class Impl;

    std::unique_ptr<Impl> pimpl;

protected:
    bool on_scroll_event (GdkEventScroll* event) override;
    void get_preferred_width_vfunc (int &minimum_width, int &natural_width) const override;
    void get_preferred_width_for_height_vfunc (int height, int &minimum_width, int &natural_width) const override;

    void on_filename_set() override;

public:
    explicit MyFileChooserButton(const Glib::ustring &title, Gtk::FileChooserAction action=Gtk::FILE_CHOOSER_ACTION_OPEN);
};

class MyFileChooserEntry : public Gtk::Box, public MyFileChooserWidget
{
public:
    explicit MyFileChooserEntry(const Glib::ustring &title, Gtk::FileChooserAction action = Gtk::FILE_CHOOSER_ACTION_OPEN);

    Glib::ustring get_placeholder_text() const;
    void set_placeholder_text(const Glib::ustring &text);

protected:
    void on_filename_set() override;

private:
    class Impl;

    std::unique_ptr<Impl> pimpl;
};

/**
 * @brief A helper method to connect the current folder property of a file chooser to an arbitrary variable.
 */
template <class FileChooser>
void bindCurrentFolder (FileChooser& chooser, Glib::ustring& variable)
{
    chooser.signal_selection_changed ().connect ([&]()
    {
        const auto current_folder = chooser.get_current_folder ();

        if (!current_folder.empty ())
            variable = current_folder;
    });

    if (!variable.empty ())
        chooser.set_current_folder (variable);
}

typedef enum RTUpdatePolicy {
    RTUP_STATIC,
    RTUP_DYNAMIC
} eUpdatePolicy;

typedef enum RTOrientation {
    RTO_Left2Right,
    RTO_Bottom2Top,
    RTO_Right2Left,
    RTO_Top2Bottom
} eRTOrientation;

typedef enum RTNav {
    NAV_NONE,
    NAV_NEXT,
    NAV_PREVIOUS
} eRTNav;

/**
 * @brief Handle the switch between text and image to be displayed in the HBox (to be used in a button/toolpanel)
 */
class TextOrIcon final : public Gtk::Box
{

public:
    TextOrIcon (const Glib::ustring &icon_name, const Glib::ustring &labelTx, const Glib::ustring &tooltipTx);
};

/**
 * Widget with image and label placed horizontally.
 */
class ImageAndLabel final : public Gtk::Box
{
    class Impl;
    std::unique_ptr<Impl> pimpl;

public:
    ImageAndLabel(const Glib::ustring& label, const Glib::ustring& iconName);
    ImageAndLabel(const Glib::ustring& label, RTImage* image);
    const RTImage* getImage() const;
    const Gtk::Label* getLabel() const;
};

/**
 * Menu item with an image and label.
 */
class MyImageMenuItemInterface
{
public:
    virtual const Gtk::Label* getLabel() const = 0;
};

/**
 * Basic image menu item.
 */
class MyImageMenuItem final : public Gtk::MenuItem, public MyImageMenuItemInterface
{
    class Impl;
    std::unique_ptr<Impl> pimpl;

public:
    MyImageMenuItem (const Glib::ustring& label, const Glib::ustring& iconName);
    MyImageMenuItem (const Glib::ustring& label, RTImage* image);
    const RTImage *getImage () const;
    const Gtk::Label* getLabel() const override;
};

/**
 * Image menu item with radio selector.
 */
class MyRadioImageMenuItem final : public Gtk::RadioMenuItem, public MyImageMenuItemInterface
{
    class Impl;
    std::unique_ptr<Impl> pimpl;

public:
    MyRadioImageMenuItem(const Glib::ustring& label, RTImage* image, Gtk::RadioButton::Group& group);
    const Gtk::Label* getLabel() const override;
};

class MyProgressBar final : public Gtk::ProgressBar
{
private:
    int w;

    void get_preferred_width_vfunc (int &minimum_width, int &natural_width) const override;
    void get_preferred_width_for_height_vfunc (int height, int &minimum_width, int &natural_width) const override;

public:
    explicit MyProgressBar(int width);
    MyProgressBar();

    void setPreferredWidth(int width);
};


/**
 * @brief Define a gradient milestone
 */
class GradientMilestone final
{
public:
    double position;
    double r;
    double g;
    double b;
    double a;

    GradientMilestone(double _p = 0., double _r = 0., double _g = 0., double _b = 0., double _a = 0.)
    {
        position = _p;
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
};

class RefCount
{
private:
    int refCount;
public:
    RefCount() : refCount(1) {}
    virtual ~RefCount() {}

    void reference()
    {
        ++refCount;
    }
    void unreference()
    {
        --refCount;

        if (!refCount) {
            delete this;
        }
    }
};

/**
 * @brief Handle back buffers as automatically as possible, and suitable to be used with Glib::RefPtr
 */
class BackBuffer : public RefCount
{

protected:
    int x, y, w, h;  // Rectangle where the colored bar has to be drawn
    rtengine::Coord offset;  // Offset of the source region to draw, relative to the top left corner
    Cairo::RefPtr<Cairo::ImageSurface> surface;
    bool dirty;  // mean that the Surface has to be (re)allocated

public:
    BackBuffer();
    BackBuffer(int w, int h, Cairo::Format format = Cairo::FORMAT_RGB24);

    // set the destination drawing rectangle; return true if the dimensions are different
    // Note: newW & newH must be > 0
    bool setDrawRectangle(Glib::RefPtr<Gdk::Window> window, Gdk::Rectangle &rectangle, bool updateBackBufferSize = true);
    bool setDrawRectangle(Glib::RefPtr<Gdk::Window> window, int newX, int newY, int newW, int newH, bool updateBackBufferSize = true);
    bool setDrawRectangle(Cairo::Format format, Gdk::Rectangle &rectangle, bool updateBackBufferSize = true);
    bool setDrawRectangle(Cairo::Format format, int newX, int newY, int newW, int newH, bool updateBackBufferSize = true);
    // set the destination drawing location, do not modify other parameters like size and offset. Use setDrawRectangle to set all parameters at the same time
    void setDestPosition(int x, int y);
    void setSrcOffset(int x, int y);
    void setSrcOffset(const rtengine::Coord &newOffset);
    void getSrcOffset(int &x, int &y);
    void getSrcOffset(rtengine::Coord &offset);

    void copyRGBCharData(const unsigned char *srcData, int srcX, int srcY, int srcW, int srcH, int srcRowStride, int dstX, int dstY);
    void copySurface(Glib::RefPtr<Gdk::Window> window, Gdk::Rectangle *rectangle = nullptr);
    void copySurface(BackBuffer *destBackBuffer, Gdk::Rectangle *rectangle = nullptr);
    void copySurface(Cairo::RefPtr<Cairo::ImageSurface> destSurface, Gdk::Rectangle *rectangle = nullptr);
    void copySurface(Cairo::RefPtr<Cairo::Context> crDest, Gdk::Rectangle *destRectangle = nullptr);

    void setDirty(bool isDirty)
    {
        dirty = isDirty;

        if (!dirty && !surface) {
            dirty = true;
        }
    }
    bool isDirty()
    {
        return dirty;
    }
    // you have to check if the surface is created thanks to surfaceCreated before starting to draw on it
    bool surfaceCreated()
    {
        return static_cast<bool>(surface);
    }
    Cairo::RefPtr<Cairo::ImageSurface> getSurface()
    {
        return surface;
    }
    void setSurface(Cairo::RefPtr<Cairo::ImageSurface> surf)
    {
        surface = surf;
    }
    void deleteSurface()
    {
        if (surface) {
            surface.clear();
        }

        dirty = true;
    }
    // will let you get a Cairo::Context for Cairo drawing operations
    Cairo::RefPtr<Cairo::Context> getContext()
    {
        return Cairo::Context::create(surface);
    }
    int getWidth()
    {
        return surface ? surface->get_width() : 0;    // sending back the allocated width
    }
    int getHeight()
    {
        return surface ? surface->get_height() : 0;    // sending back the allocated height
    }
};

/** 
 * @brief A gui element for picking spots on an image
 */ 
class SpotPicker : public Gtk::Grid
{
    private:
        int _spotHalfWidth;
        Gtk::Label _spotLabel;
        MyComboBoxText _spotSizeSetter;
        Gtk::ToggleButton _spotButton;
    public:
        SpotPicker(int const defaultValue, Glib::ustring const &buttonKey, Glib::ustring const &buttonTooltip, Glib::ustring const &labelKey);
        inline bool get_active() const
        {
            return _spotButton.get_active();
        }
        void set_active(bool b)
        {
            _spotButton.set_active(b);
        }
        int get_spot_half_width() const
        {
            return _spotHalfWidth;
        }
        int get_spot_full_width() const
        {
            return _spotHalfWidth * 2;
        }
        template <class T_return, class T_obj> void add_button_toggled_event(T_return& returnv, const T_obj function)
        {
            _spotButton.signal_toggled().connect(sigc::mem_fun(returnv, function));
        }
        bool remove_if_there(Gtk::Container* cont, bool increference = true)
        {
            return removeIfThere(cont, &_spotButton, increference);
        }

    protected:
        Gtk::Label labelSetup(Glib::ustring const &key) const;
        MyComboBoxText selecterSetup() const;
        Gtk::ToggleButton spotButtonTemplate(Glib::ustring const &key, const Glib::ustring &tooltip) const;
        void spotSizeChanged();
};

/**
 * Enforces the rule that zero or one registered toggle button is enabled at any
 * given time.
 */
class OptionalRadioButtonGroup
{
    Gtk::ToggleButton *active_button{nullptr};

    void onButtonToggled(Gtk::ToggleButton *button);

public:
    /**
     * Returns the toggle button that is active, or null if none are active.
     */
    Gtk::ToggleButton *getActiveButton() const;
    /**
     * Adds a toggle button to this group.
     *
     * If the provided button is active, any existing active button in this
     * group will be deactivated.
     */
    void register_button(Gtk::ToggleButton &button);
};

inline void setActiveTextOrIndex(Gtk::ComboBoxText &comboBox, const Glib::ustring &text, int index)
{
    bool valueSet = false;
    if (!text.empty()) {
        comboBox.set_active_text (text);
        valueSet = true;
    }

    if (!valueSet || comboBox.get_active_row_number () < 0) {
        comboBox.set_active (index);
    }
}

inline Gtk::Window& getToplevelWindow (Gtk::Widget* widget)
{
    return *static_cast<Gtk::Window*> (widget->get_toplevel ());
}