grabbing arrow keys in Gtk::Window

[Emilian Nowak <emiml wp pl>]

Hello,
I'm trying to grab key press event inside Gtk::Window
I made a signal handler for signal_key_press_event(), but this signal is
emitted when I press keys != (arrow keys).

I have attached simple test case for that. I was running it on gtkmm 2.8.8 and
pressing arrow key does nothing. I was expecting it to print "key pressed",
but something must be wrong here. 
What is correct way to catch such key pressed events?

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

bool key_pressed_callback(GdkEventKey *ek) {
	std::cout << "key pressed" << std::endl;
	return true;
}

int main(int argc, char *argv[]) {
	Gtk::Main app(&argc, &argv);

	Gtk::Window win;
	win.signal_key_press_event().connect(sigc::ptr_fun(&key_pressed_callback));
	app.run(win);

	return 0;
}