>>Hi,
>> What is the usage of Classes that created based on CONTROLS?
>>
>>Thank you
>
>Enhancing their functionality by adding new properties&methods, reusability etc.
>OOP's!
>Sergio

Controls are like Containers, with the difference that all its objects are hidden. This is very useful if you build "Containers" which functionality should be totally hidden. Thus when you use these controls on your form, you don't see its members.