I still get weird issues whether the parent panel is skinned or not. Even though the nested frame looks good in your demo, I don't want the outer panel to have any sort of border or background. In other words, I want the underlying background of the main form to show through, because with your skins it looks great! Unfortunately, if I make the parent panel a TsPanel with its SkinSection set to CHECKBOX, it looks pretty terrible during resizing. This also depends on the skin. MacMetal works a lot better than Topaz, for example. I've attached an updated demo project so you can see what I mean.
Basically I want the parent panel to be an invisible, transparent container. I only want to use it so child controls inside it know how much space they have to work with. Before using your controls, I would just use a normal TPanel and make it transparent, but ideally there would be a better way! It would be so awesome if you had a new, custom control specifically for this purpose. In other words, a transparent container (descended from TWinControl) to help group and align child controls.
[attachment=6318:Prototype.zip]