Widget toolkit - Definition and Overview

In computer programming, widget toolkits (or GUI toolkits) are sets of basic building elements for graphical user interfaces. They are often implemented as a library, or application framework.

See widget (computing) for a list of widgets.

Popular Widget Toolkits

• Low-level widget toolkits:
  • Integrated in the operating system:
    • The Mac OS toolbox, or Macintosh APIs, formerly located in ROM, but in "new world" Macs, on disk.
    • The Windows API used in Microsoft Windows
  • As a separate layer on top of the operating system:
    • The X Window System contains primitive building blocks, but they are almost always accessed using either Motif, GTK or Qt.

• High-level widget toolkits:
  • On Macintosh:
    • Cocoa - used in Mac OS X (see also Aqua)
    • MacApp Macintosh framework
    • MacZoop Macintosh C++ framework
    • Powerplant Macintosh framework
  • On MS Windows:
    • The Microsoft Foundation Classes (MFC), used by Microsoft for its own programs (Office, ...) and by most developers on the MS Windows platform
    • The Object Windows Library is sort of Borland's alternative to MFC
    • The Visual Component Library (VCL) is Borland's toolkit used in its C++ Builder and Delphi products
    • The Windows Forms is .NET's set of classes that handle GUI controls
  • On Unix, under the X Window System:
    • Xaw, the Project Athena widget set for the X Window System
    • Motif used in the Common Desktop Environment
    • Lesstif, an open source (LGPL) version of Motif
  • Cross-platform, based on the programming language Java:
    • The Abstract Windowing Toolkit is used in Java applications. It will typically use another toolkit on the selected platform in turn.
    • Swing is Sun's replacement for AWT in newer Java versions
  • Cross-platform, based on the programming languages C or C++, often with bindings to other languages:
    • Tk a widget set accessed from Tcl and other high-level script languages.
    • GTK, open source (LGPL), primarily for X Window, ported to / emulated under other platforms; used in the GNOME desktop
    • Qt, open source (GPL) under Linux / X Window, proprietary under Mac OS and MS Windows; used in KDE
    • wxWidgets (formerly wxWindows), open source (relaxed LGPL), abstracts toolkits across several platforms for C++ ,Python and Perl
    • FOX toolkit, open source (LGPL), genuinely cross-platform

• not yet categorized:
  • GNUstep
  • WINGs WINGs Is Not GNUstep
  • MetaCard
  • Standard Widget Toolkit (SWT) is Eclipse.org's toolkit used to build Eclipse, Websphere and other products

External links

• A GUI Toolkit Framework Page (http://www.geocities.com/SiliconValley/Vista/7184/guitool.html)
• Survey of Widget sets (http://www.efalk.org/Widgets/)
• GUI Toolkits for The X Window System (http://freshmeat.net/articles/view/928) (Leslie Polzer, freshmeat.net, 27 July 2003)