> would be to add enough padding so that the alignment of the struct 
> matches the largest alignment of any member of the struct. 

That might work.  I will have to think about it a bit.

> On the subject of documentation

Attached a doc patch which addresses Mark's two points plus the following:

(1) Organized things more clearly into sub-sections.
(2) Fixed up the "notes" column from the '__index__' change that
    was submitted last week.
(3) Added some examples.