Replied 9 September 2017, 8:30 am EST
I'm sorry it is not possible to modify the appointment form and add a new button in C1Scheduler at the moment. I'll try and find out if this can be done and will get back to you if I find anything.
The only possibility right now is to handle the BeforeAppointmentSave event and fetch the category/categories of the appoinment.
partial void Calendar_Created()
// Write your code here.
IContentItemProxy proxy = this.FindControl("C1Scheduler");
proxy.ControlAvailable += proxy_ControlAvailable;
void proxy_ControlAvailable(object sender, ControlAvailableEventArgs e)
var scheduler = e.Control as C1.Silverlight.Schedule.C1Scheduler;
scheduler.BeforeAppointmentSave += scheduler_BeforeAppointmentSave;
void scheduler_BeforeAppointmentSave(object sender, C1.Silverlight.Schedule.AppointmentActionEventArgs e)
var categories = e.Appointment.Categories;