Form som åbner vindue

<form>
<textarea name="a" ROWS=10, COLS=50></textarea>
<input type=button value="put i vindue"
    onClick="    x=window.open('','','height=200; width=300');
            x.document.write(this.form.a.value);
            this.form.a.value='';
            x.focus()">
</form>