Euh... now I'm having a hard time...
What I'm aiming at is:
Content is the ancestor of main
Main is the ancestor of a tabset with 2 or 3 sibling-tabs (MyTab1, MyTab2 etc)
I guess that's the first option you wrote.
The second one would be:
Content is the ancestor of main
Main is the ancestor of MyTab1
MyTab1 is the ancestor of MyTab2
And that's not what I want.
Oh! Wait! I guess I understand your hard time!
Forget my second post. I'll try to make myself clear: There is some eyetracking research out on the web that discovered people are reading text's in an F-shape; the horizontals of the F being headings and so on (as long as they understand what they are reading), the verticals of the F being the first word of every plaintext-line, and of everything they don't understand. A link: http://www.useit.com/alertbox/reading_pattern.html
I expect my backend-users to start reading the form at "Page name" and getting bored if the form appears to long.
That means a few things:
1) they would miss everything on the horizontal line of Main, Metadata etc (not only because they simply won't see it, but also because they don't understand what metadata (the second-term) are).
2) I have some formitems like startdate, starttime, enddate, endtime, contactname, contactemail, eventlocation etc. While SS is ordering formfields below eachother, it would make a pretty long form (too long for my users). So I thought about grouping them on a few tabs (a date-tab, a contact-tab etc.) It would reduce the formlength considerably, and if I order that tabset just below Navigation label (for example), it would work as a new (horizontal) 'heading' in the F-shape.
I hope this helps ;-)
(BTW: the possibility to order the shorter date- and time-fields next to each other would be a neat feature)