dblclick is a clientside event you will have to do this way to open a new window you will have to use javascript
<head runat="server">
<title>Untitled Page</title>
<script type ="text/javascript">
function test(value)
{
window.open('Newwindow.aspx?value=' + value,'_self',true);
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<input name="TextBox1" type="text" id="Text1" ondblclick="test(this.value);" />
</div>
</form>
</body>
</html>