Composite dropdownlist control that also displays a listbox????

[Peter S.]

This is driving me crazy, I am trying to build a custom dropdownlist that when
rendered also displays a listbox next to it. I am going to use the listbox as
a repository for items that are selected when accessing the dropdown. I did
override CreateControlCollection() and returned "new
ControlCollection(this);". However when I add controls (by overriding
CreateChildControls()) I do not see them on the webpage. Is there any other
magic that needs to be done? I have created other custom controls without a
problem.
BTW, I want to keep dropdownlist as the base class because my page has
a number of these controls and I want to be able to configure the list via the
aspx page rather than programatically. Any information would be greatly
appreciated!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Thanks,
Peter