Even though MDI is considered harmful, several applications (even MS Office, Adobe apps) still use it either in its pure form or some as a hybrid with a tabbed/IDE-like interface.
Is an MDI interface still appropriate for some applications?
I’m thinking of an application where one typically works with several documents at one time, and often wants to have multiple documents side to view or copy/paste between them.
An example would be Origin, where one has multiple worksheet and graph windows in a project; a tabbed or IDE-like interface would be much more inconvenient with a lot of switching back and forth.
On the mac, it’s natural and convenient for an application to have multiple top-level windows to solve this, what is the preferred way in Windows if one doesn’t use MDI?
Note that the examples you used (MS Office and Adobe applications) are big programs and have lots of features. Users will be dealing with that program, and only that program for much of the program’s lifetime.
Newer versions of MS Office (2007) and Adobe Photoshop (CS4) use multiple windows and tabs, respectively.
Note that with Windows 7, MDI’s will probably lose popularity even more because of the extra power of tabs given by Microsoft’s API’s (although you needn’t strictly use tabs — MDI windows could work, but would be more confusing for the user than usual).