set_text () is not displaying the output.

[Rodrigo Nunes <rnsribeiro gmail com>]

can 
someone tell me what's wrong with this code I'm trying to make a small 
program that gets a text typed by the user, and reversed the order of 
letters and other exhibits in Gtk:: Entry there goes the code:

main.cc

#include <iostream>
#include <gtkmm.h>

struct MyWindow : Gtk::Window
{
    MyWindow();
    void on_btn_Exit();

    void on_btn_Invert();
    void on_btn_Clear();
    
    Gtk::VBox m_vbox;
    Gtk::HBox m_hbox;
    Gtk::Entry m_Entry, m_Exit;
    Gtk::Button btnInvert, btnClear, btnExit;    
};

MyWindow::MyWindow()

: Gtk::Window(),
  m_vbox(true, 10),
  m_hbox(true, 30),
  btnInverter("Invert"),
  btnLimpar("Clear"),
  btnSair("Exit")
{
    set_title("Inverte String - Delta Inffo Informática");

    set_position(Gtk::WIN_POS_CENTER);
    set_border_width(5);
    set_size_request(400, 100);
    
    m_vbox.add(m_Entry);
    
   btnInvert.signal_clicked().connect(sigc::mem_fun(*this,
        &MyWindow::on_btn_Invert));

    m_hbox.add(btnInvert);
    
   btnClear.signal_clicked().connect(sigc::mem_fun(*this,
        &MyWindow::on_btn_Clear));
    m_hbox.add(btnClear);
    
   btnExit.signal_clicked().connect(sigc::mem_fun(*this,

        &MyWindow::on_btn_Exit));
    m_hbox.add(btnExit);
    
    m_vbox.add(m_hbox);    
    
    m_vbox.add(m_Exit);    
    
    add(m_vbox);
    
    show_all_children();
}

void MyWindow::on_btn_Invert()
{
    std::string Entry = m_Entry.get_text();        
    std::string Exit;        
    
    int size = m_Entry.get_text_length();    
    
    
    for(int x = size; x >= 0; x--){
                Exit = Exit + Entry[x];

            }                        
   
        
    m_Exit.set_text(Exit);
    
}

void MyWindow::on_btn_Clear()
{    
    m_Entry.set_text("");
    m_Exit.set_text("");    

}

void MyWindow::on_btn_Exit()
{
    hide();
}

int main(int argc, char *argv[])
{
    Gtk::Main kit(argc, argv);
    
    MyWindow window;
    
    Gtk::Main::run(window);
    

    return 0;
}