ARCHIVE: How to add a new Region to your Theme

(This topic is covered in more detail here: http://drupal.org/node/171224)

Faced recently with the need to add a new block region that spanned the right column and the center column, I hacked my way into our theme to get results, only to find those results disappearing randomly.

Finally I searched here on the Drupal site and I was NOT rewarded with a simple solution.

An obscure comment suggested putting the regions into the theme.info file, so I played, but when I added

regions[top] = 'Page Top (over content and right)'

I had the unexpected effect of loosing all other regions that my theme needed. (making navigation very difficult) :D

I checked the database for the original base theme and ended up using the following lines in my theme.info:

regions[header] = "Header"
regions[left] = "Left sidebar"
regions[top] = 'Page Top (over content right)'
regions[right] = "Right sidebar"
regions[content] = "Content"
regions[footer] = "Footer"

I'm not certain that this is the best way, in fact I find it very non-obvious that what appears to be "adding a single entry" to the regions array invalidates all previous entries, however, barring some bright young hotshot showing me what I've done wrong, the above method works.