function open_center(url, name, params, Wwidth, Wheight) {
	Swidth = screen.width;
	Sheight = screen.height;

	Wleft = Math.floor((Swidth / 2) - (Wwidth / 2) - 8);
	Wtop = Math.floor((Sheight / 2) - (Wheight / 2) - 20);

	params = params+",left="+Wleft+",top="+Wtop+",width="+Wwidth+",height="+Wheight;

	window.open(url, name, params);
}

internet = "";
function open_center_internet(url, name, params, Wwidth, Wheight) {
	var OS = navigator.platform;

	if(OS.indexOf("Win") >= 0) {
		OS = "win";
	} else if(OS.indexOf("Linux") >= 0) {
		OS = "linux";
	} else if(OS.indexOf("Mac") >= 0) {
		OS = "mac";
	}

	if(OS != "mac") {
		if(internet) {
			internet.close();
		}
	} else {
		name = name+(parseInt(Math.random()*10000000000));
	}

	Swidth = screen.width;
	Sheight = screen.height;

	Wleft = (Swidth / 2) - (Wwidth / 2) - 8;
	Wtop = (Sheight / 2) - (Wheight / 2) - 20;

	params = params+",left="+Wleft+",top="+Wtop+",width="+Wwidth+",height="+Wheight;

	if(OS != "mac") {
		internet = window.open(url, name, params);
	} else {
		window.open(url, name, params);
	}
}