var playerWin = "";
var strWidth = "400";
var strHeight = "170";
function openwin(url) {
if (playerWin != "") {playerWin.close()} // Checks for window named "playerWin", closes it if found.
leftStr = (screen.width-strWidth)/2;
topStr = (screen.height-strHeight)/2-50;
windowProperties = "toolbar=no,menubar=no,scrollbars=no,statusbar=no,height="+strHeight+",width="+strWidth+",left="+leftStr+",top="+topStr+"";
playerWin = window.open(url,'newWin',windowProperties);
}