how to disable page automatically after button post back and enable it again after post back ?

<td width="50%" align="right">
                                <asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="30" AssociatedUpdatePanelID="p1">
                                    <ProgressTemplate>

                                        <div runat="server" id="div1" class="updateprogress">
                                            <table id="Table1" runat="server" style="height: 100%; width: 100%">
                                                <tr>
                                                    <td align="center">
                                                        <img alt="" src="../Images/icon-loading.gif" />
                                                        <%--<asp:label Text="please wait" Font-Bold="true" ForeColor="Red" Font-Size="Medium" runat="server" ID="lbl"> </asp:label>--%>
                                                    </td>
                                                </tr>
                                            </table>
                                        </div>
                                    </ProgressTemplate>
                                </asp:UpdateProgress>
                                <asp:UpdatePanel runat="server" ID="p1">
                                    <ContentTemplate>
                                        <asp:Button runat="server" CssClass="Button" Text="show " ID="btn_show_inbox"
                                            OnClick="btn_show_inbox_Click" Width="200px" />
                                    </ContentTemplate>
                                </asp:UpdatePanel>
                            </td>
class updateprogress in css
.updateprogress
{
height:9000px;
width:100%;
left:0%;
top:0%;
position:fixed;
background-color:Gray;
filter:alpha(opacity=50);
}