function show_div(div_id) {
	document.getElementById('first_hovermenu_content').style.display = 'none';
	document.getElementById('second_hovermenu_content').style.display = 'none';
	document.getElementById('third_hovermenu_content').style.display = 'none';
	document.getElementById('fourth_hovermenu_content').style.display = 'none';
	
	document.getElementById(div_id).style.display = 'block';
}