<head>
<script language="javascript">
function janela() {
var abre = document.form.vbs.value;
window.open(abre,'newindow','width=510,height=410,top=116,left=80,scrollbars=yes,resize=yes');
}
function janela2() {
var abre = document.form.vbs.value;
var leftdist = 30; // distância da margem esquerda
var topdist = 30; // distância do topo
var winwidth = (window.screen.availWidth - leftdist) - 200;
var winheight = (window.screen.availHeight - topdist) - 200;
window.open(abre,'newindow','width='+winwidth+',height='+winheight+',top=0,left=0,scrollbars=yes,resize=yes');
}
</script>
<form name="form" method="POST">
<select name="vbs" size="4" class="form" style="width: 20%;font-family:verdana,arial;color:696969;font-size:8pt;" onChange="janela2();">
<option value="" selected>escolha uma opção</option>
<option value="fundo.html">link um</option>
<option value="blank.htm">link dois</option>
</form>
</head>
<body>
</body>
</html>