How to make a container control?

I've got a usercontrol named PseudoForm. It has a titlebar and a panel
named UserSpace filling all the rest. The panel is scrollable. My
intention is that other controls were inheriting from PseudForm and
that, in designer, developer could drag other controls into the
PseudoForm but into its panel.

As for now, controls can be draged into the PseudoForm but the panel
allways convers them.

I forgot tu mention it's a CF2 project. Thanks.