aspnetForm.target ='_blank'; is not working in asp.net 4
<p>I am using following code but it's not working. But in 3.5 it is working fine.
If any one can explain the reason and how can use this code effective in asp.net 4? </p>

<p><code>OnClientClick="aspnetForm.target ='_blank';"</code> </p>

<pre><code>&lt;asp:Button ID="Button1" runat="server" Text="Button" 
         onclick="Button1_Click" OnClientClick='aspnetForm.target="_blank";' /&gt;
</code></pre>

<p>code behind:</p>

<pre><code> protected void Button1_Click(object sender, EventArgs e)
    {
        Response.Redirect("Default.aspx");
    }
</code></pre>
