The LisaBar – or – Why Apple got it right.
In my new job I’m constantly forced to use Microsoft products. And while I have to admit that those products offer some quite astonishing features that can really easy your life, I constantly run into one or another wall, leaving me dazed and making me scratch my head. One of those walls is Microsoft’s inability to decide whether to use SDI or MDI.
The single document interface (SDI) is the user interface paradigm where each document consists of a single window, including its own tools and menu bars. If you have to use/view/edit multiple documents of the same type, each of these documents sits inside its own window, giving the impression that multiple instances of the application are running beside each other, even if that may not be the case. One major drawback of SDI is the increased need of screen estate; since each window has its own controls, those controls take up more space. (And no; bigger screens are no solution to that. But more of that later.)
The multiple document interface (MDI) on the other hand places all document inside a single parent window, creating the illusion of a document workplace. All document use the same toolbars and menubars. The big disadvantage of the MDI is the need for an additional window management interface; because the window manager does only know about the parent window, the application (or the toolkit) has to re-implement all the windowing functions usually provided by the window manager; window placement, window selection, window management.
Now in its long history the Microsoft Office suite has had many changes. And a lot of those changes revolved around the question whether to use SDI or MDI. In the beginning, MS Office used SDI for all its components. Then it changed them to MDI, and finally back to SDI again. But to make things worse, many components have their own definitions of how a MDI or SDI should behave. Excel for example behaves like user interface hermaphrodite, showing characteristics of both MDI and SDI. This is very confusing.
The root of all evil lies within the ways Microsoft chose to design their user interface. Back in ’84, when the first version of windows arrived in the market, Microsoft took the liberty to very generously ‘borrow’ from the Lisa user interface. Now Apple did not invent the graphical user interface, Xerox did. But that’s another story. However; when Microsoft borrowed those concepts, they knew that they were on very shaky terrain. And since they didn’t want to get into a lawsuit (which they got anyway) they changed some aspects of the user interface.
On of those aspects was the unification of the menu bar and the application interface; whereas the Apple’s document interface consisted of the whole screen, Microsoft’s document interface consisted only of the documents own windows.
Now I don’t know if Microsoft’s engineers knew what a mess they created. But by unifying toolbar and document window they created a visual ambiguity; where Apple’s interface enforced method and conduct, Microsoft’s concept created a distinction between screen and workspace. All of a sudden, the screen consisted of multiple workspaces, one for each document. And while some may, somewhat rightfully, say that this improves usability because it ties the tools to the document, it has one big drawback; all of a sudden the application is in the center of the user interface, not the document anymore.
People working with Apple computers are used to a very consistent user experience. For a large part this stems from the fact that the Lisa type of GUI does not have to fight with MDI vs. SDI. The question simply never arises, because the Lisa type of GUI does not offer the choice to create either of both; it’s something different all along. I usually think of it as ‘MDI on steroids unified with a window manager’. It virtually includes all benefits of a SDI and and the benefits of an MDI.
First of all, it saves a lot of screen space. Because the additional menubars are no more than optical bloat. “But,” you may say, “screen estate is not so important anymore. Screens get bigger and bigger, with higher resolutions and stuff.” Well, yes. But the human visual sensory equipment has limits. There is a limit of how much information you can get on a area of a certain size. And there is a limit to the area the human eye can usefully overview. And while there are people that are working with two, three or more screens, this is only the exception.
Another advantage is the document-centric approach the Lisa-type GUI takes. Documents, not applications, are the center of the desktop. No matter what kind of document you’ve opened, it never feels like you’ve ‘started’ an application. It never feels like you are using an application, rather the document itself seems to be providing the necessary tools.
The Lisa-style interface has also the advantage of the window manager knowing about all windows. There is no distinction between document windows and in-application-document windows, simply because there are no mechanisms to support such a separation; it’s policy by design. And because all windows are handled by the window manager, there are no requirements to implement such things on the toolkit or application level.
Last but not least there is Fitt’s Law. More properly termed; Fitt’s Rule. There have been many discussions about how much Fitt’s Law really applies. But in the long years I’ve been using graphical user interfaces, the rule has proved itself many times, again and again.
Microsoft may have recognised the folly of their action back in the ’80ies; Microsoft’s Office 2007 suite behaves very much like a Lisa-type user interface when in full screen. But only if in full screen. And they are constantly trying new user interface concepts. The new Internet Explorer hides the menu bar in the default configuration, don’t be surprised if it re-appears on the top of the screen in Version 8. And the new Microsoft Office 2007 plays with a interesting new concept; Ribbons. Maybe they’ll come up with something new altogether, who knows.