The Event notification occurs ANY time the control fires an event. 

This is useful for X++ language, which does not support event with parameters passed by reference.

In X++ the "Error executing code: FormActiveXControl (data source), method ... called with invalid parameters" occurs when handling events that have parameters passed by reference. Passed by reference, means that in the event handler, you can change the value for that parameter, and so the control will takes the new value, and use it. The X++ is NOT able to handle properly events with parameters by reference, so we have the solution. 

The solution is using and handling the Event notification and EventParam method., instead handling the event that gives the "invalid parameters" error executing code.