function showhide(item_id){
	block = document.getElementById('submenu'+item_id);
	switch(block.style.display){
		case 'none' : 
			block.style.display = 'block';
			break;
		case 'block' :
			block.style.display = 'none';			
			break;
		default :
			block.style.display = 'block';			
			break;
	}
}