function DefaultViewMenuHandler(scheduler, s, args) {
    if (args.item.GetItemCount() <= 0) {
        if (args.item.name == "GotoToday") {
            if (window.confirm("Are you realy want to leave this day?")) {
                scheduler.RaiseCallback("GOTODAY|" + args.item.name);
            }
        }
        else
            scheduler.RaiseCallback("MNUVIEW|" + args.item.name);
    }
}

using DevExpress.Web;
using DevExpress.Web.ASPxScheduler;
using DevExpress.XtraScheduler;
    protected void ASPxScheduler1_PopupMenuShowing(object sender, PopupMenuShowingEventArgs e) {
        ASPxSchedulerPopupMenu menu = e.Menu;
        if (menu.MenuId.Equals(SchedulerMenuItemId.DefaultMenu)) {
            menu.ClientSideEvents.ItemClick = String.Format("function(s, e) {{ DefaultViewMenuHandler({0}, s, e); }}", ASPxScheduler1.ClientInstanceName);
            MenuItemCollection menuItems = menu.Items;
            MenuItem defaultItem = menuItems.FindByName("NewAppointment");
            defaultItem.Name = "MyNewAppointment";
            defaultItem.Text = "Instant Appointment";
        }
    }

Imports DevExpress.Web
Imports DevExpress.Web.ASPxScheduler
Imports DevExpress.XtraScheduler
    Protected Sub ASPxScheduler1_PopupMenuShowing(ByVal sender As Object, ByVal e As PopupMenuShowingEventArgs)
        Dim menu As ASPxSchedulerPopupMenu = e.Menu
        If menu.MenuId.Equals(SchedulerMenuItemId.DefaultMenu) Then
            menu.ClientSideEvents.ItemClick = String.Format("function(s, e) {{ DefaultViewMenuHandler({0}, s, e); }}", ASPxScheduler1.ClientInstanceName)
            Dim menuItems As MenuItemCollection = menu.Items
            Dim defaultItem As MenuItem = menuItems.FindByName("NewAppointment")
            defaultItem.Name = "MyNewAppointment"
            defaultItem.Text = "Instant Appointment"
        End If
    End Sub

using DevExpress.Web;
using DevExpress.Web.ASPxScheduler;
using DevExpress.XtraScheduler;
    protected void ASPxScheduler1_BeforeExecuteCallbackCommand(object sender, SchedulerCallbackCommandEventArgs e) {
        if(e.CommandId == "MNUVIEW")
            e.Command = new CustomMenuViewCallbackCommand(ASPxScheduler1);
    }
public class CustomMenuViewCallbackCommand : DevExpress.Web.ASPxScheduler.Internal.MenuViewCallbackCommand {
    string menuItemName;

    public CustomMenuViewCallbackCommand(ASPxScheduler control)
        : base(control) {
    }

    public string MenuItemName { get { return menuItemName; } }

    protected override void ParseParameters(string parameters) {
        this.menuItemName = parameters;
        base.ParseParameters(parameters);
    }
    protected override void ExecuteCore() {
        ExecuteUserMenuCommand(MenuItemName);
        base.ExecuteCore();
    }
    protected internal virtual void ExecuteUserMenuCommand(string MenuItemName) {
        if(MenuItemName == "MyNewAppointment")
            CreateAppointment("New Appointment", AppointmentStatusType.Free, 1);
    }
    protected void CreateAppointment(string subject, AppointmentStatusType statusType, int labelId) {
        Appointment apt = Control.Storage.CreateAppointment(AppointmentType.Normal);
        apt.Subject = subject;
        apt.Start = Control.SelectedInterval.Start;
        apt.End = Control.SelectedInterval.End;
        apt.ResourceId = Control.SelectedResource.Id;
        apt.StatusKey = (int)statusType;
        apt.LabelKey = labelId;
        Control.Storage.Appointments.Add(apt);
    }
}

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="DefaultObjectDataSources.ascx.cs" Inherits="DefaultObjectDataSources" %>
<asp:ObjectDataSource ID="appointmentDataSourceObject" runat="server" DataObjectTypeName="CustomEvent" TypeName="CustomEventDataSource" DeleteMethod="DeleteMethodHandler" SelectMethod="SelectMethodHandler" InsertMethod="InsertMethodHandler" OnObjectCreated="temporaryAppointmentDataSource_ObjectCreated" UpdateMethod="UpdateMethodHandler">
</asp:ObjectDataSource>
<asp:ObjectDataSource ID="resourceDataSourceObject" runat="server" DataObjectTypeName="CustomResource" TypeName="CustomResourceDataSource" DeleteMethod="DeleteMethodHandler" SelectMethod="SelectMethodHandler" InsertMethod="InsertMethodHandler" OnObjectCreated="temporaryResourceDataSource_ObjectCreated" UpdateMethod="UpdateMethodHandler">
</asp:ObjectDataSource>

Imports DevExpress.Web
Imports DevExpress.Web.ASPxScheduler
Imports DevExpress.XtraScheduler
    Protected Sub ASPxScheduler1_BeforeExecuteCallbackCommand(ByVal sender As Object, ByVal e As SchedulerCallbackCommandEventArgs)
        If e.CommandId = "MNUVIEW" Then
            e.Command = New CustomMenuViewCallbackCommand(ASPxScheduler1)
        End If
    End Sub
Public Class CustomMenuViewCallbackCommand
    Inherits DevExpress.Web.ASPxScheduler.Internal.MenuViewCallbackCommand

    Private menuItemName_Renamed As String

    Public Sub New(ByVal control As ASPxScheduler)
        MyBase.New(control)
    End Sub

    Public ReadOnly Property MenuItemName() As String
        Get
            Return menuItemName_Renamed
        End Get
    End Property

    Protected Overrides Sub ParseParameters(ByVal parameters As String)
        Me.menuItemName_Renamed = parameters
        MyBase.ParseParameters(parameters)
    End Sub
    Protected Overrides Sub ExecuteCore()
        ExecuteUserMenuCommand(MenuItemName)
        MyBase.ExecuteCore()
    End Sub
    Protected Friend Overridable Sub ExecuteUserMenuCommand(ByVal MenuItemName As String)
        If MenuItemName = "MyNewAppointment" Then
            CreateAppointment("New Appointment", AppointmentStatusType.Free, 1)
        End If
    End Sub
    Protected Sub CreateAppointment(ByVal subject As String, ByVal statusType As AppointmentStatusType, ByVal labelId As Integer)
        Dim apt As Appointment = Control.Storage.CreateAppointment(AppointmentType.Normal)
        apt.Subject = subject
        apt.Start = Control.SelectedInterval.Start
        apt.End = Control.SelectedInterval.End
        apt.ResourceId = Control.SelectedResource.Id
        apt.StatusKey = CInt((statusType))
        apt.LabelKey = labelId
        Control.Storage.Appointments.Add(apt)
    End Sub
End Class

<%@ Control Language="vb" AutoEventWireup="true" CodeFile="DefaultObjectDataSources.ascx.vb" Inherits="DefaultObjectDataSources" %>
<asp:ObjectDataSource ID="appointmentDataSourceObject" runat="server" DataObjectTypeName="CustomEvent" TypeName="CustomEventDataSource" DeleteMethod="DeleteMethodHandler" SelectMethod="SelectMethodHandler" InsertMethod="InsertMethodHandler" OnObjectCreated="temporaryAppointmentDataSource_ObjectCreated" UpdateMethod="UpdateMethodHandler">
</asp:ObjectDataSource>
<asp:ObjectDataSource ID="resourceDataSourceObject" runat="server" DataObjectTypeName="CustomResource" TypeName="CustomResourceDataSource" DeleteMethod="DeleteMethodHandler" SelectMethod="SelectMethodHandler" InsertMethod="InsertMethodHandler" OnObjectCreated="temporaryResourceDataSource_ObjectCreated" UpdateMethod="UpdateMethodHandler">
</asp:ObjectDataSource>