That ol' consistency black magic

by Neil Lee

As countless interface designers and usability experts keep pointing out, consistency in your application is a key method of improving user friendliness and overall usability: Establish one way of doing something, and then stick to that throughout your application. This way, your customers get used to how your application works and reacts, usability and productivity goes up, and everyone's smiling.

One of the key strengths of Apple's design in the past was the overall attention to consistency and a particular attention to the little details. Mac OS X is still leagues beyond any other operating system available in the design and consistency department, but with every release of Mac OS X teeny gaps have started to appear in Apple's, er, armor. Okay, that metaphor is rather weak, but I'm still working on my first coffee of the day, so cut me some slack...

Here's a perfect example, as found in Apple's Mail:

When I control+click on my Junk mail folder and select "Delete Junk Mail", I get a dialog asking for confirmation:

Mail Junk

But if I do the same and empty Mail's trash, I get a sheet instead of a dialog:

Mail trash

According to Apple's Human Interface Guidelines:

"A sheet is document modal—that is while it is open the user is prevented from doing anything else in the window, or document, until the dialog is dismissed. In contrast, a dialog that is application modal prevents the user from doing anything else within the application."

In this case, both the sheet and the dialog prevent usage of the application, as the sheet is attached to the main Mail window and not a separate document window. So why the inconsistency?

I totally agree that this is nitpicking, but in my opinion it's little inconsistencies like this that add up. It's reasonably easy to nail consistency for the bigger things (like the overall look and feel of an application), but, as the saying goes, god is in the details.

I'd love to find out if this inconsistency is a bug, or if it's done on purpose, and if so, why.


2005-08-15 11:44:34
Another dumb one
Here's my least favourite bit of interface stupidity: attempting to delete a song in iTunes brings up a dialog with the text: "Do you want to move the selected items to the Trash, or keep them in the iTunes music folder? Only files in the iTunes Music Folder will be moved to the Trash." "Cancel" "Keep Files" "Move to Trash." Perhaps I'm simply getting stupid in my dotage, but I had to try it to find out that "Keep Files" does indeed keep them on disk, but removes them from the Library listing; how is this useful? And what files other than those in the iTunes Music Folder could we be referring to?

Possibly an idiot,


2005-08-15 12:29:27
Not entirely correct
While I agree with you that this is inconsistent (even if junk and trashed are not exactly the same), I should point out that the sheet doesn't prevent usage of the application. In fact you can still open another Viewer Window (what you call Main Window).
Just for completeness :)
2005-08-15 14:18:54
More inconsistency
While I'm ranting, what exactly is the "close" button (or Cmd-W) supposed to do? In things like iPhoto and Disk Utililty it quits the app; in other applications it closes the current window. Presumably there's some sort of arcane logic here; I'd prefer consistent behaviour.


2005-08-15 15:54:34
Yet more inconsistency
Even worse IMHO is the inconsistency in the button labeling. Buttons should be labeled according to the action they cause, so it's clear what's going to happen. Using Yes and No is a definite no-no ;-) because the button names themselves give no useful information in themselves. Both sets of buttons should be labeled Cancel and Erase.

Apple's own Guidelines say "Button names should correspond to the action the user performs when pressing the button—for example, Erase, Save, or Delete."

Using Yes and No is just plain dangerous.

2005-08-15 18:29:03
Re: Another dumb one
Because not everyone uses iTunes to organize their music collection. :-) It is an option to leave files where they are instead of moving them to an iTunes organized structure. That's handy if you use multiple music players.

For example, on my Powermac I just use iTunes, but on my Windows box I tend to use iTunes and Winamp. Also, I might want to play a file once (say a podcast) in iTunes, but then take it out of the iTunes library so that it doesn't show up in a random shuffle.

2005-08-15 20:20:19
More inconsistency
There is logic there. The rule is this:

If the application typically makes use of multiple windows (Finder, Safari, Mail, etc.), then closing the last window doesn't quit the app. After all, the app can have any number of windows open, and zero is just another possible number.

If the application typically uses only one window (Calculator, Disk Utility, etc.), then closing that window is a pretty clear sign that the user is done with things. Closing the window quits the app.

I think it's not a bad rule. The problem: I don't think Apple clearly explains this rule, and it's not obvious to many users. I also don't know how well developers follow the rule; I'll bet there are some glaring exceptions.

2005-08-16 07:07:32
Re: Another dumb one
I understand what you're saying, but if you do use iTunes for organization, you now have orphan files: the file is still in the iTunes Music directory, it just doesn't show up in the Library window, and there doesn't seem to be a way to force an update/resynch. Since this choice shows up (along with the weird "Only files in the iTunes Music folder..." message) for people using the default configureation, it strikes me as bad (and confusing) UI design. YMMV.
2005-08-16 07:20:10
More inconsistency
I'd say that iTunes and iPhoto are pretty glaring exceptions, and, without meaning to be rude, I think it is is a bad rule: violates the good ole Principle of Least Surprise. I've never seen multiple iTunes windows (although there's lots of stuff I've never seen), yet Cmd-W does not quit the app. iPhoto does employ multiple windows; Cmd-W closes the app. So, clicking that red Stop button up there does different things, apparently at random. Am I missing something here?
2005-08-16 16:05:00
More inconsistency
iTunes can have multiple windows. I don't really like them, but I've run into them with shared music lists.

I don't like that closing the iPhoto window quits the app. It's already painfully slow to start, so I wantit to stay alive. I just don't want the window on the screen. I'd rather not have to remember who needs to close windows and who needs to minimize them to get that. Only quit if I tell you to!

2005-08-18 10:16:25
Re: Another dumb one
You could always try the File --> Add to Library... menu option in iTunes and have it search your iTunes music directory to pick any orphans.
2005-08-19 00:13:49
The real consistency disaster is the sidebar. For example, drag a folder onto BBEdit and you get a file browser window.

Try doing the same thing from the sidebar, nothing happens except the folder disappearing into a puff of smoke. So what you do is what you normally do when you are moving a folder, and suddenly realize you don't want to move it: push escape to cancel the action. BUT NO. Pushing Escape in this case completes the action of deleting the Sidebar folder. This would be a bit like having a dialogue with 'Delete', 'Not Delete' pressing ESC and having the object deleted. Nuts.