var WinNum;

  function neues_popup(url,name,breit,hoch,scroll,menubar) {
    var fname = name+WinNum;
    fenster = window.open(url,fname,'width='+breit+',height='+hoch+',left=10,top=10,toolbar=no,status=no,menubar='+menubar+',scrollbars='+scroll+',resizable=yes,copyhistory=no');
	if (WinNum==0) { WinNum=1; } else { WinNum=0; }
    	if (typeof fenster != "undefined") { fenster.focus(); }
  }

function popup(url,name,breit,hoch,scroll,menubar)
{
    if (typeof fenster == "undefined" || fenster.closed) {
      	neues_popup(url,name,breit,hoch,scroll,menubar);
    	} else {
        	fenster.close();
        	neues_popup(url,name,breit,hoch,scroll,menubar);
    	}
 }