function switch_start_menue (id1, id2) { 
	if (document.getElementById) { 
		var obj1 = document.getElementById(id1);
		obj1.style.display = (obj1.style.display=='block'?'none':'block');
		var obj2 = document.getElementById(id2);
		obj2.style.display = (obj2.style.display=='block'?'none':'block');
	} 
}

function switch_tab_menue (id) { 

		switch(id) {
			case 'start_menue_t1':
			document.getElementById('start_menue_t1').style.display = 'block';
			document.getElementById('start_menue_t2').style.display = 'none';
			document.getElementById('start_menue_t3').style.display = 'none';
			break;
			
			case 'start_menue_t2':
			document.getElementById('start_menue_t1').style.display = 'none';
			document.getElementById('start_menue_t2').style.display = 'block';
			document.getElementById('start_menue_t3').style.display = 'none';
			break;
			
			case 'start_menue_t3':
			document.getElementById('start_menue_t1').style.display = 'none';
			document.getElementById('start_menue_t2').style.display = 'none';
			document.getElementById('start_menue_t3').style.display = 'block';
			break;			
		}
}



var GB_ROOT_DIR = "./survey/greybox/";