VS2010 is less restrictive in this respect. In fact I don't think there are any restrictions - even defining regions that would make no sense in real coding are allowed. e.g.: This will work in 2008 and 2010:

#region A
    public class C1
    {
    #endregion
    }

wheras this will fail in 2008:

public class C2
    {
             #region B
    }
#endregion

In 2010 even something like this will work:

public class C2
    {
        public void Foo()
        {
            #region B
        }
    }
#endregion

But, bottom line, you usually need a region to contain only complete code blocks and 2008 handles that OK. Arguably, 2010 is worse since it's possible to define regions that work as specified but are actually conffusing since they expand/collapse arbitrary code selections...

>A little futzing revealed the answer:
>
>When I put all of the child #endregions within the curly brace that teminates the class, alll was well.
>
>>>I have a large class with a lot of methods (I probably will break it up the next time I add to it) and I have used #region foomethods / #endregion pairs to make it more readable.
>When I nest more than 4 pairs in a parent pair, the class compiles OK but the - and + marks don't appear on the 5th region and I can't expand or collapse it.
>Is that a limit or am I doing something odd again?