event handler
An 
Event handler is a public 
Method of a 
Class that is called each time an 
Event is raised by an 
Object having an observer of the same 
Class.
The name of the event handler is the "event name" of the 
Object, followed by an underscore, and the name of the event.
The event name of an object is usually the name you define in the development environment, but can be anything you want.
This name is attributed at object creation by the 
NEW instruction.
Sample
hButton = NEW Button(ME) AS "MyButton"
...
PUBLIC PROCEDURE MyButton_Click()
  PRINT "My button was clicked !"
END
In this case, the "event name" is 
"MyButton", which was defined for the 
Object hButton of the 
Class Button.
The name of the event handler 
MyButton_Click() is formed from the "event name" 
"MyButton", followed by an underscore and the name of the event 
Click.
See also