function open_win(url, myWidth, myHeight) 
{
	//myWidth = 600;
	//myHeight = 500;
	myLeft = (screen.width/2) - (myWidth/2);
	myTop = (screen.height/2) - (myHeight/2);
	window.open(url, "", "height=" + myHeight + ", width=" + myWidth + ", left=" + myLeft + ", top=" + myTop + ", toolbar=no, menubar=no");
}