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Strange connection between ViewState and DropDownList's SelectedIndexChanged event

Posted By:      Posted Date: September 20, 2010    Points: 0   Category :ASP.Net

So, I have this code (just for example):

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <form id="form1" runat="server">
        <asp:Label ID="Label1" runat="server" Text="Sort by:"></asp:Label>
        <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
            <asp:ListItem Value="A" Text="A"></asp:ListItem>
            <asp:ListItem Value="B" Text="B"></asp:ListItem>
            <asp:ListItem Value="C" Text="C"></asp:ListItem>
            <asp:ListItem Value="D" Text="D"></asp:ListItem>
        <asp:GridView ID="GridView1" runat="server" onsorting="GridView1_Sorting">

The Code-behind file looks like that:

public partial class _Default : Syst

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