Example of non-blocking execution in GTK with Vala (run with `vala --pkg=gtk+-3 example.vala`)

example.vala

using Gtk;
Button button;

public static int main (string[] args) {
	Gtk.init (ref args);

	var window = new Window ();
	window.title = "Count without blocking the UI";
	window.border_width = 10;
	window.window_position = WindowPosition.CENTER;
	window.set_default_size (350, 70);
	window.destroy.connect (Gtk.main_quit);
	button = new Button.with_label ("Start counting");
	button.clicked.connect (() => {
		count ();
	});

	window.add (button);
	window.show_all ();

	Gtk.main ();

	return 0;
}

async void count(){
	for(int i = 0; i < 10000; i++){
		button.label = i.to_string();
		Idle.add (count.callback);
		yield;
	}
}