>I need to detect what the user does.
>I have a custom class that it activates only with the changes of focus of the windows, made by users, and I can't detect those changes of focus.
>Did you understand?
Precisely, Form.Activate() an Event, and it is supposed to fire whenever the user makes the form active (and also by a programmatic activation). IOW, any code that should react to a form being activated should go into Form.Activate().
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)