Question

How do I implement the OnUnhandledException event. It does not seem to exist in your object model?

Answer

The event must be implement in code. The event catches exceptions raised in the draw loop. Since all parts of the gantt has possiblity to inject user code in draw loop, all parts has this event.

In c# write 

Gantt.Grid.OnUnhandledException+= and press tab
Gantt.TimeItemArea.OnUnhandledException+= and press tab
Gantt.DateScaler.OnUnhandledException+= and press tab