FLTK/Disabling the escape key

FLTK applications automatically exit when pressing the Escape key. To disable this behaviour on the main window, a custom callback must replace the default one:

#include <fltk/events.h>
#include <fltk/run.h>
#include <fltk/Window.h>
 
#include <cstdlib>
 
void window_callback (fltk::Widget*) {
 
        if (fltk::event() == fltk::KEY && fltk::event_key() == fltk::EscapeKey) {
                // don't do anything when the Escape key is pressed
        } else {
                // exit when the user closes the window
                exit(0);
        }
}
 
 
int main (int argc, char** argv) {
 
        fltk::Window window (300, 300, "FLTK test");
 
        // set our own callback
        window.callback (window_callback);
 
        window.show (argc, argv);
        return fltk::run();
}