Tabs ≠ MDI

The ridiculous Firefox/Opera rivalry (it’s software, not religion) has given rise to one annoyingly persistent meme: the belief that tabs are just MDI (Multiple Document Interface).

They’re not.

MDI, as implemented in many Windows applications and eventually abandoned by Microsoft, involves having a mini-desktop inside your application, with its own windows that you can minimize, maximize, and rearrange. If you have a taskbar-like interface it can look a lot like tabs, and you can certainly use it the same way as tabs, but it’s a different UI paradigm.

A tabbed interface is very specific. You have only one view at a time in your application window, and you switch between them based on a row (or column) of tabs along the window’s edge. You can look at it as a proper subset of MDI, but it is not the same thing.

Additionally, classical MDI uses one master window for the application. All documents appear in that window. Tabbed interfaces often (though not always) allow you to have more than one window, each with its own set of tabs. This makes it possible to group documents, web pages, etc. by category in a way that you can’t with a single-document interface or classic MDI.

So when people claim Opera had tabs first, they’re thinking of MDI—which Opera did have before Mozilla did. Tabs were showing up in browsers like Netcaptor and Galeon, however, long before they showed up in the Mozilla suite—and long before Opera hid its MDI capabilities under a tab-like veneer.

(reposted from Spread Firefox in response to Asa Dotzler’s post on the history of tabbed browsing)

10 thoughts on “Tabs ≠ MDI

  1. Tabber

    Tabs aren’t “just MDI”. Like MDI, tabbed interfaces keep pages in the main window. The difference is that while plain MDI doesn’t have a task bar, tabbed browsers do. Opera 4 had that. Just because it was skinned to make tabs look like buttons doesn’t mean that they didn’t have the same purpose: To switch between pages.

    So yes, Opera did have tabbed browsing before Mozilla. Everyone recognizes this fact, perhaps except a few Firefox apologists.

    It gets very silly when you try to redefine things:

    “A tabbed interface is very specific. You have only one view at a time in your application window, and you switch between them based on a row (or column) of tabs along the window’s edge.”

    A tabbed interface has a bar which is used to switch between views/pages. That’s it. You are just trying to narrow it down to something it isn’t to mislead your readers.

    “You can look at it as a proper subset of MDI, but it is not the same thing.”

    Correct. The difference is the “task bar”, which Opera 4 had.

    Reply
  2. Kelson Post author

    Oh, you caught me! Nothing I say matters because I’m a Firefox apologist! A Firefox apologist who uses Safari and Opera on a regular basis, has a “Get Opera” button next to the “Get Firefox” button on his website, and promotes the “Viewable in any browser” campaign.

    And even better, I’m trying to mislead my readers! All five of them!

    As I said in Asa’s comment thread, if adding a taskbar to a windowing system makes it a tabbed interface, then Windows 95 had a tabbed interface for its desktop.

    Reply
  3. jp10558

    I see. I agree, it is a different UI for tabbed browsing vs MDI with a page/window/tab bar. What I really don’t get is why people would think Tabs (which are inherently limited as shown) would be better than full MDI with the tab bar for a more powerful interface?

    I use Opera 99% of the time as a tabbed browser. But it’s nice to have popups in the same window, that keep the proper sizes. It’s nice to be able to put two pages next to each other occasionally. And it’s helpful to be able to switch between two open pages by clicking on one tab (like programs in windows). In fact, the only sort of annoying thing is the pages that display after closing a page. And even then, I find there are as many benefits from treating pages as a stack of windows as there are from the FF method.

    I also say that in 95% of the cases, Opera 4’s MDI + Page bar and FF Tab browsing would work the same for the user.

    Reply
  4. DV

    Hi:

    Would you please clarify this statement ‘…MDI, as implemented in many Windows applications and eventually abandoned by Microsoft, involves ….”

    I would like to know the reasons behind MS plan to abandon MDI as you indicated.

    Thanks,

    DV

    Reply
  5. Kelson Post author

    I was thinking of Office, specifically Word and Excel (Microsoft’s flagship applications). If you go back to Office 95 and earlier, everything’s MDI. There’s one window for Word, and all your open documents are inside it. There’s one window for Excel, and all your open spreadsheets are inside that one. With Office 2000, they shifted away from it. There, and in Office XP, Word is entirely SDI (single document interface). If you have two Word documents open, you have two Word windows. Excel is a bit odd in that you have only one Excel window, but each spreadsheet has its own button on the taskbar.

    “Abandoned” was probably the wrong word. “Downplayed” would have been more accurate.

    Reply
  6. D

    In my opinion, MDI is much more versatile than a tabbed interface. It can do everything that a tabbed interface can do — and more. Opera could and still can do everything that a “real” tabbed browser can, but it can also show you several web pages tiled, cascaded, etc.

    IMO, the difference as far as who had “tabbed browsing” first is in semantics, and Opera had all the functionality of a tabbed browser before Firefox. On the other hand, I can do things like minimize a sub-window, tile windows side by side, cascade windows, etc. in Opera that I cannot do in Firefox.

    Furthermore, Opera has always trapped any and all pop-up windows inside of the parent window, and there is no way for them to “escape” out of the frame without you manually opening a new one. This is very valuable to me.

    Firefox has many other pros that I like. There are many extensions that I don’t know how I used to live without. But as far as who had “tabbed browsing” first, I think the prize does not go to Firefox.

    Reply
  7. rox0r

    A way old post but more info:

    Every post in this thread seems to think that MDI means only one window. There is nothing preventing people from making a Multiple Document Interface with Multiple windows. Then you can organize Windows to have similar documents inside them.

    Reply

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