Here's another UI pet-peeve entry: source lists don't belong in drawers.
First, let's get on the same page and see what Apple says about the appropriate use of drawers:
A drawer should contain frequently accessed controls that don’t need to be visible at all times. [Apple HI Guidelines]
Of course, Apple's guidelines offer some abiguity:
Some uses of a drawer are similar to uses of a source list. [Apple HI Guidelines]
And here's what it has to say about source lists:
A source list is an area of window set off by a movable pane splitter to provide users a way to navigate data. Use a source list when the data presented in it is a primary means of navigating within the application. [Apple HI Guidelines]
The ambiguity comes from this line:
Some examples of uses of drawers include access to favorites lists, the Mailbox drawer (in the Mail application), or browser bookmarks. [Apple HI Guidelines]
So, because Apple's Mail.app was already written to use drawers, the guidelines were written to promote drawers in this use case...!
The problem here is that the mailbox (source) list is not secondary to the usability of the product, unless you have only one inbox, no trash, draft or sent boxes, and zero folders! For most users, the source list in this drawer need to be visible all the time, because they're integral to the workflow of using mail.
Apple apparently understand this now... here's a screenshot of Apple Mail.app in Tiger:
As you can see on the left, Apple has dropped the drawer and put the mailbox (source) list inside the main window. This fits the workflow much better. Apple will have to update their guidelines to at least not point to Mail.app as an example of drawers, and hopefully better explain when to use drawers and when to use source lists.
Apple's own mis-use of drawers has lead third party developers to do the same. One example is MarsEdit:
I would contend that the list being displayed in the drawer (on the right!) is a source list, and so should be displayed inside the main window (on the left). Some might argue that users with only one weblog wouldn't need to see the list, but that misses something important: the Drafts list! A user will need to easily move between drafts and posted entries.
Just for contrast, here is the edit window in MarsEdit, which shows an excellent use-case for drawers!
