GNUstep is a cross-platform, object oriented environment composed of frameworks, tools, and servers (daemons). It is very similar to the Cocoa frameworks from Apple, and tries to maintain compatibility with Cocoa wherever it is desired and possible. The frameworks provide classes for containers, distributed objects, object archiving, file management, text system, font management, image composition, WYSIWYG PostScript graphics, and more.
Gorm (Graphic Object Relationship Modeller) is a GNUstep application for building user interfaces and application objects relationships. Its major features include drag-and-drop creation of GUI elements from palettes, run-time loading of additional palettes, direct on-screen manipulation of GUI elements, manipulation and examination of objects via inspectors, and creation of connections between objects using mouse. It is a clone of the former NeXTstep (currently OS X) "Interface Builder" application.
jGRASP integrates the Control Structure Diagram (CSD) seamlessly and unobtrusively into source-code editing for Java, C, C++, Objective-C, Ada, and VHDL. The CSD is a control flow and data structure diagram that fits into the space normally taken by indentation in source code. Its intention is to improve the readability of source code. The CSD also enables source code folding in a meaningful way, based on code structures. jGRASP provides lots of editing features, an integrated Java debugger, UML dependency diagrams for Java, configurable colors and font size, and click-to-error for compile and runtime (Java stack dumps) errors.
Tk Drag and Drop is an extension for Tcl/Tk to add native drag and drop capabilities to the Tk toolkit. It is designed for Tk versions 8.3.3 and higher. Native drag and drop are supported under Microsoft Windows (XP, Vista, 7), Mac OS X Leopard (Cocoa framework), and Linux (XDND, drag support missing).