In the area of graphical user interfaces, a tabbed document interface (TDI) is one that allows multiple panes of information to be contained within a single master windows, using tabs to navigate between them. The name TDI implies similarity to the Microsoft Windows standards for MDI and SDI, but TDI does not form part of the Microsoft Windows User Interface Guidelines.
The term document does not strictly have to refer to a document, and indeed the most widely-used applications for TDI are web browsers that do not employ a traditional document metaphor at all. Similarly, instant messenger and terminal applications are often implemented as TDI.
Tabbed browsing
Web browsers are notable for implementing this kind of interface (called tabbed browsing). BookLink Technologies pioneered this interface design in its InternetWorks browser in 1994. Independently, the founders of Opera built an MDI-based browser in the same year (via a technical preview not available publicly; a public release was made in 1996). The tabbed interface approach was then followed by the Internet Explorer shell NetCaptor in 1997. These pioneers were followed by a number of others like IBrowse in 1999, Opera in 2000 (with the release of version 4), Mozilla in 2001 (through the MultiZilla extension in April of 2001 and a built-in tabbed browsing mode added to Mozilla 0.9.5 in October of 2001), Konqueror 3.1 in January 2003, and Safari in 2003. As of 2006, most graphical web browsers support a tabbed interface, including the beta of Internet Explorer 7. Software, such as the freeware AM Browser, is also available to add a TDI around earlier versions of Internet Explorer. OmniWeb version 5, released August 2004, includes visual tabbed browsing which displays preview images of pages in a drawer to the left or right of the main browser window. Avant Browser, Maxthon and Slim Browser are some of the most popular tabbed browsers using Internet Explorer's rendering engine.
Compliance To Windows User Interface Guidelines
There is some debate about how the TDI interface fits in with the Microsoft Windows User Interface Guidelines. In many ways the Workgroup window management model most closely resembles TDI. However this is a relatively recent addition to the Windows User Interface Guidelines, and most developers still prefer to view SDI or MDI as the primary document models for Windows.
Comparison to SDI
Advantages
One important advantage of the tabbed document interface is that it holds many different documents logically under the one window, instead of holding a large number of small child windows. Another is that sets of related documents can be grouped within each of several windows. Using tabs instead of new windows to display content creates a smaller memory footprint and therefore reduces the strain on the operating system (however, opening several tabs at once will temporarily bog down the system). Tabbed web browsers often allow users to save their browsing session and return to it later.
Disadvantage
Although the tabbed document interface does allow for multiple views under one window, there are problems with this interface. One such problem is dealing with many tabs at once. When a window is tabbed to a certain number that exceeds the available resolution of the monitor, the tabs clutter up (this is the same problem as with SDI but moved to another place in the user interface).
Multi-row tabs are a second issue that will appear in menu dialogs in some programs. Dealing with multiple rows of tabs in one window has two disadvanges:
- It creates excess window clutter
- It complicates what should be an easy-to-read dialog
Finding a specific tab in a 3 or 4 level tabular interface can be difficult for some people. Part of the issue with this difficulty lies in the lack of any sorting scheme. Tabs can be strewn about without any sense of order, thus looking for a tab provides no meaningful understanding of a position to a tab relative to other tabs. Additionally, the clutter created by mutiple tabs can create a dialog that is unusually small, with the tabs above it dominating the window.
Thus, although tabbed windows work great in environments where there is a minimal necessity for tabs (around ten tabs or less), this scheme does not scale, and additional widgets can be required to convey the information in a legible manner.
Comparison to MDI
Advantages
For people used to SDI, MDI can be confusing as windows can be hidden behind other windows. Some MDI applications lack a taskbar or menu to allow quick access to all windows, so in some cases a window can only be found by closing all others. TDI windows ("tabs") are always maximized, and all TDI applications have a taskbar or menu to allow direct access to any tab. It is nearly impossible for windows to get "lost" inside TDI.
Disadvantages
TDI windows must always be maximized inside their parent window, and as a result two tabs cannot be visible at the same time. This makes comparing of documents or easy copy-and-pasting between two documents more difficult. Full MDI interfaces allow for tiling or cascading of child windows, and do not suffer from these limitations.
One example of an application that allows either TDI or MDI browsing is the Opera web browser. Using TDI by default, this application also supports full MDI and can also run as an SDI application. Mozilla Firefox uses a hybrid system where each window can have multiple tabs.
In order to mitigate these problems, some integrated development environments, such as recent versions of XEmacs and Microsoft's Visual Studio, provide a hybrid interface which allows splitting the parent window into multiple MDI-like "panes," each with their own separate TDI tab set. The Ion window manager does the same for the entire desktop.This provides many of the advantages of both MDI and TDI, although it can still be difficult for users to get used to.
Example programs
Web browsers
Text editors
Spreadsheet programs
Presentation program
Instant messengers
Terminal program
Window managers
Web applications
See also