[TGUI, SFML 2.1] Problem z handle event w gui.

#include <TGUI\TGUI.hpp>
#include <SFML\Graphics.hpp>

int main()
{
    // Create the window
    sf::RenderWindow window( sf::VideoMode( 1280, 777 ), "TGUI window" );
    tgui::Gui gui( window );
   
    // Load the font (you should check the return value to make sure that it is loaded)
    gui.setGlobalFont( "DejaVuSans.ttf" );
   
    // Load the widgets
    gui.loadWidgetsFromFile( "form.txt" );
   
    // Main loop
    while( window.isOpen() )
    {
        sf::Event event;
        while( window.pollEvent( event ) )
        {
            if( event.type == sf::Event::Closed )
                 window.close();
           
            // Pass the event to all the widgets
            gui.handleEvent( event );
        }
       
        // The callback loop
        tgui::Callback callback;
        while( gui.pollCallback( callback ) )
        {
            // Make sure tha callback comes from the button
            if( callback.id == 1 )
            {
                // Get the username and password
               
                // Continue here by checking if the username and password are correct ...
            }
        }
       
        window.clear();
       
        // Draw all created widgets
        gui.draw();
       
        window.display();
    }
   
    return EXIT_SUCCESS;
}