<asp:TemplateField>
<ItemTemplate>
      <asp:TextBox ID="InvoiceDateTextBox" runat="server"  Text="<%# Bind('date') %>"></asp:TextBox> 
	<asp:panel runat = "server" ID = "Panel1" Style="display: none">
					<asp:calendar id="Calendar1" runat="server" BorderWidth="1px" Width="130px" 
                                                 BackColor="Beige" Font-Size="8pt" ForeColor="Indigo" DayNameFormat="FirstLetter" 
                                                 Height="150px" Font-Names="Verdana" BorderColor="DeepSkyBlue" ShowGridLines="True">
						<TodayDayStyle ForeColor="White" BackColor="DodgerBlue"></TodayDayStyle>
						<SelectorStyle BackColor="Magenta"></SelectorStyle>
						<DayStyle BackColor="Beige"></DayStyle>
						<NextPrevStyle Font-Size="9pt" ForeColor="#FFFFCC"></NextPrevStyle>
						<DayHeaderStyle Height="1px" BackColor="DeepSkyBlue"></DayHeaderStyle>
						<SelectedDayStyle Font-Bold="True" BackColor="red"></SelectedDayStyle>
						<TitleStyle BackColor="DodgerBlue" ForeColor="White"></TitleStyle>
						<WeekendDayStyle BackColor="MistyRose"></WeekendDayStyle>
						<OtherMonthDayStyle ForeColor="Silver"></OtherMonthDayStyle>
					</asp:calendar>
</asp:panel>

				<act:PopupControlExtender ID = "PopupExtender1" runat = "server"
						TargetControlID = "InvoiceDateTextBox"
						PopupControlID = "Panel1"
						Position = "Bottom" OffsetX="6" OffsetY="0" />
					            <Animations>
					                <OnShow>
					                    <Sequence>
					                        <HideAction Visible="true" />
					                        <FadeIn Duration="5.5" Fps="20" />
					                    </Sequence>
					                </OnShow>
					                <OnHide>
					                  <FadeOut Duration="5.5" Fps="20" />
					                </OnHide>
					            </Animations>
				</act:PopupControlExtender>
	</ItemTemplate>
</asp:TemplateField>

Protected Sub Calendar1_SelectionChanged(sender As Object, e As EventArgs)
    PopupControlExtender.Commit(Calendar1.SelectedDate.ToShortDateString())
End Sub