Print first n lines from a file

main-window.cc

void MainWindow::show_message()
{
	std::stringstream title, content;
	title << "The first [" << m_spin_button.get_value_as_int() << "] lines";
	Gtk::MessageDialog dialog(title.str());

	std::ifstream file;
	file.open(m_file_chooser_button.get_filename().c_str(), std::ifstream::in);
	char buffer[512];
	short i = 0;
	
	content << "Are: " << std::endl;
	while (i < m_spin_button.get_value_as_int() ) {
		file.getline(buffer, 512);
		content << "[" << buffer << "]" << std::endl;
		i += 1;
	}
	dialog.set_secondary_text(content.str());
	dialog.run();
}