var prev;
var currWindow;
function pop (URL,windowName,widthV,heightV)
{
	if (prev != undefined) prev.close();
	var curr = windowName;
	if (widthV==null) widthV="800";
	if (heightV==null) heightV="600";	
	currWindow = window.open(URL,curr,'width=' + widthV +',height='+heightV+',location=0,menubar=0,scrollbars=1,status=0,toolbar=0,resizable=0,left=450,top=200');
	currWindow.document.body.leftMargin = currWindow.document.body.topMargin = 3;
	prev = currWindow;
}