# File gtkglext/sample/gtkglut.rb, line 150
    def GLUT.KeyboardFunc(keyboard)
        if keyboard
            @@window.signal_connect_after("key_press_event") do |i, e|
                keyval = nil
                case e.keyval
                    when Gdk::Keyval::GDK_Escape then keyval = 27
                    else keyval = e.keyval
                end
                # TODO: get the cursor pos
                keyboard.call(keyval, 0, 0)
            end
        else
            @@window.signal_connect_after("key_press_event") { |i, e| }
        end
    end