Thank you for writing.
To achieve this, you can use the AppointmentEditDialogShowing
event. The following code snippet demonstrates this:
sender, AppointmentEditDialogShowingEventArgs e)
"Are you sure want to add an appointment?"
"Are you sure"
MessageBoxButtons.YesNo, RadMessageIcon.Question) == DialogResult.No)
I hope you find this useful. Do not hesitate to write back, if you have any additional questions.
the Telerik team