protected void RadScheduler1_AppointmentInsert(object sender, Telerik.Web.UI.SchedulerCancelEventArgs e)
{
string test = e.Appointment.Attributes["Test"];
???? here to get values from listbox???
}
<telerik:RadScheduler ID="RadScheduler1" runat="server" Height="583px"
Width="889px" onappointmentcreated="RadScheduler1_AppointmentCreated"
onappointmentinsert="RadScheduler1_AppointmentInsert" CustomAttributeNames="Test,Test2">
<AdvancedInsertTemplate >
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Bind("Subject") %>'></asp:TextBox>
<asp:ListBox ID="ListBox1" runat="server" SelectionMode="Multiple" SelectedValue='<%# Bind("Test") %>'><asp:ListItem>dsdsd</asp:ListItem><asp:ListItem>sdsdsd</asp:ListItem></asp:ListBox>
<asp:LinkButton runat="server" ID="UpdateButton" CssClass="rsAdvEditSave" CommandName="Insert">Insert</asp:LinkButton>
</AdvancedInsertTemplate>
<AdvancedEditTemplate>
hello
</AdvancedEditTemplate>
</telerik:RadScheduler>