JavaScript

You can create a submenu by adding "items" property to a menu item:

var menu = new DayPilot.Menu({items: [
  {text:"Show event start", onClick: function(args) {alert("Event start: " + args.source.start());} },
  {text:"Details", items: [
    {text:"Show event ID", onClick: function(args) {alert("Event value: " + args.source.value());} },
    {text:"Show event text", onClick: function(args) {alert("Event text: " + args.source.text());} }
  ]}
]});

ASP.NET WebForms

 
<daypilot:daypilotmenu id="DayPilotMenu1" runat="server" CssClassPrefix="menu_default" ShowMenuTitle="true">
  <DayPilot:MenuItem Text="Open" Action="JavaScript" JavaScript="edit(e);" ></DayPilot:MenuItem>
  <DayPilot:MenuItem Text="Send" Action="JavaScript" JavaScript="alert('Sending event (id ' + e.value() +')');" ></DayPilot:MenuItem>
  <DayPilot:MenuItem Text="Details" >
      <DayPilot:MenuItem Action="JavaScript" JavaScript="alert('test');" Text="Test" />
  </DayPilot:MenuItem>
</daypilot:daypilotmenu>