Dynamic Window construction in WPF

Hi,

I'm interested in dynamic composition of a Window.  Not dynamic in that known controls re-size or re-position themselves, but dynamic in the sense that the Window needs to be "assembled" at run time from a set of known custom controls.

Can this be done in xaml, or do I have to revert to creating the dynamic parts of the UI in the code-behind of the Window via normal class instantiation and property setting?

Thanks.

Steve