Trouble using response.redirect - asp.net

Question

Hi and sorry for my poor english.
I have an Asp.net + Vb.Net application and here is an example of code illustrating my problem :
First I have Default.aspx page with 2 buttons, "Valid" and "Redirect"
Protected Sub butvalid_Click(sender As Object, e As EventArgs) Handles butvalid.Click
If (File.Exists(Server.MapPath("log.txt"))) Then
Dim lines() As String = IO.File.ReadAllLines(Server.MapPath("log.txt"))
Dim tmp As Integer = Convert.ToInt32(lines(lines.Length - 1))
tmp = tmp + 1
File.AppendAllText(Server.MapPath("log.txt"), Environment.NewLine & tmp.ToString)
Else
File.WriteAllText(Server.MapPath("log.txt"), "1")
End If
End Sub
Protected Sub Redirect_Click(sender As Object, e As EventArgs) Handles Redirect.Click
Response.Redirect("accueil.aspx")
End Sub
Valid button write into a txt file and Redirect is redirecting ...
Here is the page_load code of accueil.aspx :
Threading.Thread.Sleep(3000)
Response.Redirect("default.aspx")
The problem is when I click on Redirect button in Default.aspx page, the valid button remains accessible and user can click on Valid button.
How can I disable Valid button after Redirect click ?
Thanks in advance.

Answer 1

Place this in Page_OnLoad handler and fire at each postback to make sure it is bound. This will disable the button on the client side, and when the page load fires again after the click is and response to the server is done, the button will be enabled again.
Redirect.Attributes.Add("onclick", "javascript:"
+ butvalid.ClientID + ".disabled=true;"
+ Page.ClientScript.GetPostBackEventReference(Redirect, null));