Fired before an attribute of an edge is changed. Note for LGSPBackend: Because graph elements of the LGSPBackend don't know their graph a call to LGSPGraphElement.SetAttribute will not fire this event. If you use this function and want the event to be fired, you have to fire it yourself using ChangingEdgeAttributes.
Assembly: libGr (Module: libGr) Version: 188.8.131.52 (184.108.40.206)
event ChangingEdgeAttributeHandler OnChangingEdgeAttribute