Container and child control

Hi,

I have a control (let's called it : Container) which include several
"Child" controls.

1. I would like to detect if a child control is out of the display
rectangle of the container.
If yes, i would like to know if it is horizontally or vertically. Based
on that, i would like to display the appropriate scrollbar (horizontal
and/or vertical)

2. How can I know what should be re-painted ?
I mean, if my container scrolls somehow the child controls, i need to
know which rectangle should be redrawn and which child controls belong
to this rectangle to redraw.

thanks a lot,

Al.