var PAGE_TO_OPEN = '/30min_warn.html';

var MINUTES = 30;
var SECONDS = 0;

var cmin2,csec2;

function Down() {
	cmin2= MINUTES;
	csec2= SECONDS;
	
	DownRepeat(); 
}

function DownRepeat() {
	csec2--;
	if(csec2==-1) { csec2=59; cmin2--; }
			
	if((cmin2==0)&&(csec2==0)) {
		openPopup( PAGE_TO_OPEN, 'timerwarning','width=550,height=323,resizable=yes'); 
	}
	
	else down=setTimeout("DownRepeat()",1000); 
}