how to get key press event in goocanvasmm

["Klaus Rudolph" <lts-rudolph gmx de>]

Is it possible to receive key press events in canvas?

The following signal handler is not called inside goocanvas. It compiles fine but it is not called if a key 
is pressed.


Exmaple:


Glib::RefPtr<Goocanvas::Item> root;

class MyCanvas: public Goocanvas::Canvas
{
    double scale = 1;

    bool on_key_press_event( GdkEventKey* event ) override
    {
        std::cout << "on_key_press_event" << std::endl;
        return true;
    }

};

int main(int argc, char* argv[])
{
    Gtk::Main app(&argc, &argv);
    Goocanvas::init("example", "0.1", argc, argv);

    Gtk::Window win;

    MyCanvas m_canvas;
    m_canvas.set_size_request(640, 480);
    m_canvas.set_bounds(0, 0, 800, 800);
    root = m_canvas.get_root_item();

    //--------------------------------

    Glib::RefPtr<Goocanvas::Ellipse> outer = Goocanvas::Ellipse::create( 100,100,20,20);
    outer->property_line_width() = 5;
    outer->property_stroke_color() = "red";
    outer->property_fill_color()="blue";
    root->add_child( outer );

    win.add( m_canvas);
    win.show_all_children();


    Gtk::Main::run(win);
    return 0;
}