removing autolayout it loose constraint on resize

I have an autolayout in the main frame that contains other frames
When I drag the cursor over the frame in autolayout to resize it, it resizes all the content (other frames) towards the center and it is right that it behaves like this.
I tried deleting autolayout on the main frame and then putting it back without changing anything and this time when I resize, it no longer behaves as before, but the frame in the autolayout moves to the right without resizing. Why? What about this behaviour? Davide