SWT

SWT, or Standard Widget Toolkit, is a graphical widget toolkit for the Java platform. It was originally developed by IBM as part of the Eclipse project and is now maintained by the Eclipse Foundation. SWT provides native look and feel and performance by invoking the host operating system's GUI libraries through the Java Native Interface rather than rendering all widgets itself.

SWT's architecture centers on a small set of core classes such as Display, Shell, and Composite, and a wide range of platform widgets like Button, Label, Text, List, and Tree. The toolkit uses the operating system's widgets on Windows (Win32), macOS (Cocoa), and Linux/Unix (GTK) to render GUI elements. Applications create a Display, then a Shell as the main window, build a widget tree, and run an event loop to process user input and paint events.

SWT is commonly used in the Eclipse IDE and in other Java applications requiring a native-like appearance and efficient interaction with the host OS. It contrasts with Swing, which renders widgets in Java rather than delegating to native widgets. The project is released under the Eclipse Public License and is available as open source. While SWT offers advantages in native look and potential performance, it requires platform-specific native libraries, which can introduce OS-dependent behavior and additional build considerations.