I could not wait any longer for a reply.  This looks like an unsupported, incomplete (not to mention buggy dev interface that crashes) product.  I purchased Dundas Guage, very powerful and robust.

I too was looking for this. I was really hoping to see something along the lines of

needle.ValueChangedHandler += myValueChangedHandler(object sender, ValueChangedEventArgs e );

Any chance to see this in a future version?

 the UltraGauge control has a MarkerValueChanged event.

Does that mean that all the code posted by David Negley is not necessary? 

I will try this today.

Thanks

it is necessary if you want to make needles draggable on a linear gauge.

This is a unique need.