Events in oops ALV

Hi abap gurus,

I'm having a small doubt regarding events in class cl_gui_alv_grid_display. Generally for a event to be triggered we follow these steps:

1.define a class for event handling.

2.define a method for a particular event in that class and then implement that class.

3.create object for that class.

4.register the event by using set_handler.

My doubt is that whenever we do a particular action how that particular event is getting raised i.e., where Raise event code has been written

because user_command event has been raised in raise_event of class cl_gui_alv_grid but this method is not accessed in any of the class or method

still how that event is raising and in debugging mode if i keep break point in this method it is not triggering for user command event.

Regards,

Rakesh reddy challa.