[Usability]Question on Multiple Document Interfaces

[Bart Kelsey <bart osc edu>]

The HIG document mentions that Multiple Document Interfaces have 
"inherent usability problems."  As an experienced user, however, I 
should point out that multiple documents (especially using tabs at the 
top of the screen) tend to make my user experience a lot more pleasant 
and convenient.  Switching windows is generally more cumbersome than 
switching tabs if you're trying to edit or view many documents at once.

I realize that a Single Document Interface may be easier for a new user 
to understand, but why not add an option in the Preferences dialog 
(defaulted to single documents) that allows more experienced users to 
opt to use the application in MDI mode?

Along the same lines, what exactly *are* the usabilty problems with MDI?

Bart