MrEd is a graphical implementation of the Scheme programming language for Windows (95 and up), Mac OS X (10.3 and up) and Unix/X. GUI applications written using MrEd run on all supported platforms without modification.

MrEd provides a windowing toolbox for creating windows and menus; a drawing toolbox for drawing to windows, bitmaps, and printer devices; and an editor toolbox for creating multimedia editors.

MrEd's GUI toolbox is integrated with a thread system. MrEd dispatches each GUI event to the handler thread via synchronous (single-threaded) callback procedures, but MrEd also supports multiple eventspaces, which permit asynchronous (multi-threaded) event handling among different sets of windows.

System Requirements: Windows (95 and up), Mac OS X (10.3 and up), or Unix running the X Window System. MrEd is useful given at least 30 MB of RAM.