function wikiopen(){
var breite = screen.width;
var hoehe = screen.height;
var left = 0; var top = 0;
if(breite <= 640) { } else {
left = (breite-640)/2; top = (hoehe-400)/2; }
var wikiopen = window.open("","wikipedia","width=640,height=400,left="+left+",top="+top+",locationbar=0,location=0,menubar=0,directories=0,favorites=0,status=0,statusbar=0,scrollbars=1,resizable=1");
}