function open_win(href,name,b0,h0) { 

var breite = screen.width;
var hoehe = screen.height;
var pos_x = (breite/2)-(b0/2);
var pos_y = (hoehe/2)-(h0/2);

newWindow = window.open(href,name,"scrollbars=yes,status=no,toolbar=no,location=no,directories=no,resizable=no,menubar=no,width="+b0+",height="+h0+",top="+pos_y+",left="+pos_x);
newWindow.focus();
};