FLTK/停用 Escape 鍵

按下 Escape 鍵時，FLTK 應用程式會自動退出。若要停用主視窗上的此行為，自定義回撥必須替代預設回撥

#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();
}