TGUI Chatbox Problem

#include <iostream>

#include <SFML/Graphics.hpp>

#include <TGUI/TGUI.hpp>

int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 450), "TGUI");
    window.setVerticalSyncEnabled(true);

    tgui::Gui gui(window);

    gui.setGlobalFont("visitor1.ttf");

    tgui::ChatBox::Ptr chatbox(gui);
    chatbox->load("data/tgui/widgets/White.conf");
    chatbox->setPosition({ 100.f, 100.f });
    chatbox->setSize(300.f, 300.f);
    chatbox->addLine("Test", sf::Color::Black);
    chatbox->addLine("Test2", sf::Color::Black);
    chatbox->addLine("ASFASF", sf::Color::Black);

    gui.saveWidgetsToFile("test.txt");

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();

            gui.handleEvent(event);
        }

        tgui::Callback callback;
        while (gui.pollCallback(callback))
        {

        }

        window.clear();
        gui.draw();
        window.display();
    }


    return 0;
}