GUI/main/main.cpp

#include <FL/Fl.H>
#include <FL/Fl_Window.H>
#include <FL/Fl_Button.H>
#include <iostream>


using namespace std;

void button_cb(Fl_Widget* wid){
    Fl_Button* but = (Fl_Button*)wid;

    if(but->label()=="&Good job"){
        but->label("&Click me");
    } else
        but->label("&Good job");
    but->redraw();
}

int main(int argc, char **argv) {
  Fl_Window win(300,200,"Testing");
  int i = 7;
  win.begin();
  Fl_Button but(20,150,70,30,"&Click me");
  win.end();
  but.callback(button_cb);
  win.show();
  return Fl::run();
}