I have created a UserControl that has 3 panels.
What I what to do is expose one of the panels to the Visual Studio designer so you can drop controls inside that panel.
Currently I have the UserControl on a form but dragging say a text box over it will have the text box paint over the UserControl and not be a part of the user control.
Surgery is required to make the nested panel designable. The steps are explained well in this blog post.