var ShowX_ = (screen.width/2)-220;
var ShowY_ = (screen.height/2)-225;
var pos_ = "left="+ShowX_+",top="+ShowY_;
function dopopup(file,typbez){
link = "bild.asp?bild=" + file + "&typ=" + typbez;
dopopupWindow = window.open(link,"Maschinenbilder","scrollbars=yes,width=440,height=450,"+pos_);
}