I’ve just finished the Your First App tutorial for OS X. Except I notice that in the final section on “Polish”, the effect of resizing the window is not at all like the expected screenshot.
That shot has a text field at the top, a button at the bottom, and a vertical slider in between. My slider has an undeleteable(?) constraint of a fixed height, the height I made it when I first dropped it on the form. So when I shrink the window, I get truncation

As I said, I can’t delete or switch to “Less than or equals” the constraint on the vertical slider. What do I do here to get intelligent auto-layout?
OK, Apple seems to be a little slow in updating their Tutorials. If you are deploying to [Mountain] Lion, the resizing works with the constraints differently than implied in the Tutorial. I got the desired effect by
The observed behavior now matches expectations. Hope this helps someone else.