Is there anyway to keep it on the same X-axis; rather than floating all over the form?

An example of what I want is in Internet Explorer 5.0

a. Open Favourites or History. Notice it is separated by a band in the screen.
b. Select the band and resize the objects. All you have is a simple verticle line which does not move off of the X-Axis. It seems to be contained within a specific amount of space.

I have attempted what you suggested in a container, but I can still float the object over the remainder of the form.

Any suggestions would be greatly appreciated.