Multiple document interface

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Graphical computer applications with a multiple document interface (MDI) are those whose windows reside under a single parent window (usually with the exception of modal windows), as opposed to all windows being separate from each other (single document interface). The initialism MDI is usually not expanded. In the usability community, there has been much debate over which interface type is preferable. Generally SDI is seen as more useful in cases where users work with more than one application. Companies have used both interfaces with mixed responses. For example, Microsoft has changed its Office applications from SDI to MDI mode and then back to SDI, although the degree of implementation varies from one component to another.

The disadvantage of MDI usually cited is the lack of information about the currently opened windows: In order to view a list of windows open in MDI applications, the user typically has to select a specific menu ("window list" or something similar), if this option is available at all. With an SDI application, the window manager's task bar or task manager displays the currently opened windows. In recent years, applications have increasingly added "task-bars" and "tabs" to show the currently opened windows in an MDI application, which has made this criticism somewhat obsolete. Some people use a different name for this interface, "tabbed document interface" (TDI). When tabs are used to manage windows, individual ones usually cannot be resized.

Nearly all graphical user interface toolkits to date provide at least one solution for designing MDIs. The Java GUI toolkit, Swing, for instance, provides the class javax.swing.JDesktopPane which serves as a container for individual frames (class javax.swing.JInternalFrame). GTK+ lacks any standardized support for MDI.

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[edit] Compared to single document interface

[edit] Advantages

  • With MDI (and also TDI), a single menu bar and/or toolbar is shared between all child windows, reducing clutter and increasing efficient use of screen space.
  • An application's child windows can be hidden/shown/minimized/maximized as a whole.
  • Features such as "Tile" and "Cascade" can be implemented for the child windows.
  • Possibly faster and more memory efficient, since the application is shared, and only the document changes. the speed of switching between the internal windows is usually faster than having the OS switch between external windows.
  • Some applications have keyboard shortcuts to quickly jump to the functionality you need (faster navigating), and this doesn't need the OS or window manager support, since it happens inside the application.

[edit] Disadvantages

  • Can be tricky to implement on desktops using multiple monitors as the parent window may need to span two or more monitors.
  • Virtual desktops cannot be spanned by children of the MDI. However, in some cases, this is solveable by initiating another parent window; this is the case in Opera, for example, which allows tabs/child windows to be dragged outside of the parent window to start their own parent window (on Windows). In other cases, each child window is also a parent window, forming a new, "virtual" MDI[1].
  • MDI can make it more difficult to work with several applications at once, by restricting the ways in which windows from multiple applications can be arranged together.
  • Without an MDI frame window, floating toolbars from one application can clutter the workspace of other applications, potentially confusing users with the jumble of interfaces.
  • The shared menu might change, which may cause confusion to some users.
  • MDI child windows behave differently from those in single document interface applications, requiring users to learn two subtly different windowing concepts. Similarly, the MDI parent window behaves like the desktop in many respects, but has enough differences to confuse some users.
  • Many window managers have built-in support for manipulating groups of separate windows, which is typically more flexible than MDI in that windows can be grouped and ungrouped arbitrarily. A typical policy is to group automatically windows that belong to the same application. This arguably makes MDI redundant by providing a solution to the same problem.

[edit] Application examples

  • Internet Explorer 6: This is a typical SDI application
  • Visual Studio 6 development environment: This is a typical modern implementation of MDI
  • Visual Studio .NET: MDI or TDI with "Window" menu, but not both
  • Firefox: TDI by default, can be SDI instead
  • Opera: MDI combined with TDI (note: on Mac OS X, as of Opera version 9.27, there is no MDI, just TDI)
  • GIMP: Floating windows (limited MDI is available via "Deweirdifier" plugin)
  • GIMPshop: A fork of the GIMP edited to be more user-friendly for Adobe Photoshop users. Note: the Windows version (still in beta form) has the "Deweirdifier" plug in built-in
  • Adobe Photoshop: Floating windows in Mac version; MDI in Windows XP version. In newer versions of Photoshop, toolbars can move outside the frame window. Child windows can be outside of the frame unless they are minimized or maximized.
  • Adobe Acrobat: Purely MDI until version 7.0. (Microsoft Windows version only)
  • Microsoft Excel 2003: Excel is SDI if you start new instances of the application, but classic MDI if you click the "File → New" menu (except the child windows optionally appear on the OS taskbar)
  • Microsoft Word 2003: Up to Office 97, Word (Windows version) was MDI. However, from 2000 onwards, Word is a Multiple Top-Level Windows Interface application, thus exposing to shell as many individual SDI instances while the operating system recognizes it as a single instance of an MDI Application. In Word 2000 this was the only interface available, but from 2002 onwards the traditional MDI was available again as an option. The Mac OS version of Word (the only non-Windows OS to be supported) has never used MDI. MFC (which Microsoft Office is loosely based upon) supports this metaphor from version 7.0, as a new Feature in Visual Studio 2002.
  • UltraEdit: Combination of MDI & TDI (a true MDI interface with a tab bar for quick access).
  • VEDIT: Combination of MDI & TDI (a true MDI interface with a tab bar for quick access). Special "Full size" windows act like maximized windows, but allow smaller overlapping windows to be used at the same time. Multiple instances of Vedit can be started, which allows it to be used like an SDI application.
  • Notepad++, PSPad, TextMate and many other text editors: TDI
  • EmEditor: Options for either SDI or MDI.
  • Macromedia Studio under Windows uses a hybrid interface. If document windows are maximized, as they are by default, the program presents a TDI, however, if the windows are un-maximized it presents an MDI.
  • Corel Wordperfect: MDI, although a user can open multiple instances of WP with a single document in each, if they wish to. Recent versions maintain a list of open documents for a given window on the status bar at the bottom of the window, providing a variant of the TDI.


[edit] IDE-style interface

Graphical computer applications with an IDE-style interface (IDE) are those whose child windows reside under a single parent window (usually with the exception of modal windows). An IDE-style interface is distinguishable form of Multiple Document Interface (MDI), because all child windows in an IDE-style interface are enhanced with added functionality not ordinarily available in MDI applications. Because of this, IDE-style applications can be considered a functional superset and descendant of MDI applications.

Examples of enhanced child-window functionality include:

  • Dockable child windows
  • Collapsable child windows
  • Tabbed document interface for sub-panes
  • Independent sub-panes of the parent window
  • GUI splitters to resize sub-panes of the parent window
  • Persistence for window arrangements

[edit] Collapsable child windows

A common convention for child windows in IDE-style applications is the ability to collapse child windows, either when inactive, or when specified by the user. Child windows that are collapsed will conform to one of the four outer boundaries of the parent window, with some kind of label or indicator that allows them to be expanded again.

[edit] Tabbed document interface for sub-panes

In contrast to (MDI) applications, which ordinarily allow a single tabbed interface for the parent window, applications with an IDE-style interface allow tabs for organizing one or more subpanes of the parent window.

[edit] IDE-style application examples

[edit] Mac OS X

An MDI saves screen real estate by eliminating redundant menu bars on Mac OS X, because the Mac OS X GUI is application-centric instead of window-centric. As opposed to Windows, all windows belonging to an application share the same menu. These windows can be hidden and manipulated as a group, and the Dock switches between applications (i.e., groups of windows) instead of between individual windows. (Switching between windows is possible by clicking, by Exposé, and by Command-`)

However, TDIs and even some MDI-like implementations (such as Photoshop's) do eliminate UI redundancies and can lighten up the application's memory weight.

[edit] See also

[edit] External links

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