hi,
What you want to do can be done by redrawing the middle portion of the mainframe dynamically (i.e. at runtime).
I am just elaborating what Richard says in second part of his answer.
Make a mainframe.This mainframe will be a container which will hold your child windows.
And make 4 child windows top, bottom, middle1 and middle2 .
The child windows middle1 and middle2 will be dynamically created at run time based on some condition (for example initially middle1 was being displayed but when user inputs 'Next' in the bottom window, middle1 is destroyed and middle2 is drawn in its place) while top and bottom window can remain fixed at their positions.
Now you you need to know how to create the child windows dynamically.you can google for it .
You can start by having a look at this
code project article[
^]