WebControlWrapper.EventIsImplemented
From Xojo Documentation
Method
WebControlWrapper.EventIsImplemented(ObjectType as Introspection.TypeInfo, EventName as String) As Boolean
New in 2012r2
Supported for all project types and targets.
New in 2012r2
Supported for all project types and targets.
Returns True if the current instance implements the specified event.
Notes
This method is very important to the efficient operation of the Web Framework. It is designed to be a way to detect whether or not a developer using a control actually has the need for a certain kind of data from a control at runtime. For example, if you were creating a signature capture control using a canvas control, while there may be some worth to getting every "pen stroke" for some users, others might just want the resulting signature. By not implementing the MouseMove event, there is no reason to even send those events to the server.
Example
Assuming you were creating a class named HTMLArea, you could find out if the user had implemented the MouseMove event like this: