Puoi sfruttare l'evento selected item...(però ci devi clicare...VEDI L'ESEMPIO)
codice:
<%@ Page Language="VB" %>
<html>
<head>
<script runat="server">
Sub OnSelectionChanged (sender as Object, e as EventArgs)
lblSelDate.Text = Calendar1.SelectedDate
End Sub
</script>
</head>
<body>
<h3><font face="Verdana">Calendar control demo</font></h3>
<form runat="server">
<asp:Calendar id=”Calendar1” runat="server"
SelectionMode="DayWeekMonth"
Font-Name="Verdana;Arial" Font-Size="12px"
Height="180px" Width="230px"
TodayDayStyle-Font-Bold="True"
DayHeaderStyle-Font-Bold="True"
OtherMonthDayStyle-ForeColor="gray"
TitleStyle-BackColor="#3366ff"
TitleStyle-ForeColor="white"
TitleStyle-Font-Bold="True"
SelectedDayStyle-BackColor="#ffcc66"
SelectedDayStyle-Font-Bold="True"
NextPrevFormat="ShortMonth"
NextPrevStyle-ForeColor="white"
NextPrevStyle-Font-Size="10px"
SelectorStyle-BackColor="#99ccff"
SelectorStyle-ForeColor="navy"
SelectorStyle-Font-Size="9px"
SelectWeekText = "wk"
SelectMonthText = "month"
OnSelectionChanged="OnSelectionChanged"
/>
<asp:label style="font-name:Verdana;font-size:12px;forecolor:gray" id=”lblSelDate” runat="server"/>
</form>
</body>
</html>