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Windows Forms Layout Options

Visual Studio .NET 2003

If you've been using Windows-based applications for a while, you've probably noticed that not all user interfaces look or behave the same. There are three main styles:

  • the single-document interface (SDI)
  • the multiple-document interface (MDI)
  • the Explorer-style interface

An example of the SDI interface is the WordPad application included with Microsoft Windows. In WordPad, only a single document can be open; you must close one document in order to open another.

WordPad, a single-document interface (SDI) application


Microsoft Excel is an example of an MDI interface; it allows you to display multiple documents at the same time, with each document displayed in its own window. You can recognize an MDI application by the inclusion of a Window menu containing commands for switching between windows or documents.

Microsoft Excel, a multiple-document interface (MDI) application


In determining which interface style is best, you need to look at the purpose of the application. An application for processing insurance claims might lend itself to the MDI style — a clerk is likely to be working on more than one claim at a time or might need to compare two claims. On the other hand, a calendar application would be best suited to the SDI style — it's not likely that you would need more than one calendar open at a time; in the rare event that you did, you could open a second instance of the SDI application.

The SDI style is the more common layout option for Windows applications. There are a number of considerations and techniques unique to creating MDI applications, which are addressed in Multiple-Document Interface (MDI) Applications.

In addition to the two most common interface styles, SDI and MDI, a third interface style is becoming more popular: the Explorer-style interface. The Explorer-style interface is a single window containing two panes or regions, usually consisting of a tree or hierarchical view on the left and a display area on the right, as in the Microsoft Windows Explorer. This type of interface lends itself to navigating or browsing large numbers of documents, pictures, or files.

The Windows Explorer, an explorer-style interface


See Also

Introduction to Windows Forms | Creating Windows Forms | Displaying Windows Forms in the Designer | What's New in Windows Forms and Controls