option scroll for draggables

option scroll for draggables


Regarding the scroll option for the draggable constructor method I am
puzzeled and would appreciate if someone can clarify it.
From documentation: http://jqueryui.com/demos/draggable/#option-scroll
1-) Demo says that scroll refer to viewport:
*Automatically scroll the document when the draggable is moved beyond
the viewport.*
and the code sample says it refer to the container:
*If set to true, container auto-scrolls while dragging.*
Is container the viewport? or the parent element of the draggable
object?
2-) The default value for scroll is true.
If I set scroll: false nothing happens! scroll is automatic as well.
Finally, how does scroll works?
Explanation and example, if possible, will be very appreciate and
thaks a lot.