IsPostBack and method="get"

 take this simple .aspx file:

<%@ Page Language="C#" EnableViewState="false"  AutoEventWireup="true"  EnableSessionState="False" CodeBehind="Default.aspx.cs" Inherits="WebApplication3._Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server" method="get">
    <div>
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <a ...