Sets the start event of a trend pen. This function only operates on an event-based trend.
TrnSetEvent(AN, Pen, Event)
The AN of the chosen trend.
The trend pen number:
0 - The pen currently in focus
1...8 - Pen1. . .Pen8
The number of the start event.
0 (zero) if successful, otherwise an error is returned.
TrnGetEvent, TrnGetCluster, TrnGetCursorEvent
! Sets pen1 to event number 123456
! Scrolls pen1 back by 100 events