At this moment you have to switch to manual message displaying using .message() - http://api.daypilot.org/daypilot-calendar-message/, AfterRenderJavaScript, and Update(object):
.aspx
<DayPilot:DayPilotCalendar
...
AfterRenderJavaScript="afterRender(data, isCallBack)"
ClientObjectName="dpc"
/>
function afterRender(data, isCallBack) {
if (data.message) {
dpc.message(data.message, 20000, "#fff", "#dc143c");;
}
}
.aspx.cs
Hashtable data = new Hashtable();
data["message"] = "Welcome!";
DayPilotCalendar1.Update(data);
A convenient message bar customization is planned for DayPilot Pro for ASP.NET WebForms 7.0:
http://www.daypilot.org/daypilot-pro-for-asp-net-webforms-7-0.html