Hi Larry,
You can override the style of the appointment popup window by writing style targeted ScheduleAppointmentEditorControl.
The steps you need to follow is
1) Just override the style of the schedule control. Schedule alone is enough; other inner controls are not needed.
2) There you can find Property AppointmentEditorStyle in DaysView, MonthView and ScheduleView. Just assign key of the style of your own.
3) Set the new style of the schedule in your sample.
I have attached a sample for this.
Thanks,
Abdul Rahman
CustomAppointmentWindowSample_4581359b.zip