DiaCanvas is a generalized version of the drawing canvas used by DIA. It extends some features used by DIA and adds new ones, while preserving as many of the original features as possible. This project is no longer actively maintained. It is suggested that you try DiaCanvas2 instead.
GTK, which stands for the Gimp ToolKit, is a library for creating graphical user interfaces. It is designed to be small and efficient, but still flexible enough to allow the programmer freedom in the interfaces created. GTK provides some unique features over standard widget libraries.
Open Motif Everywhere is the standard distribution of Open Motif built from the official Open Group sources for Open Motif. It has been ported to all popular Linux (and BSD) environments. Most modern distributions of Linux and BSD include the stable release. Annual support contracts are also available.
Qt is a comprehensive, object-oriented development framework that enables development of high-performance, cross-platform rich-client and server-side applications. When you implement a program with Qt, you can run it on the X Window System (Unix/X11), Apple Mac OS X, and Microsoft Windows NT/9x/2000/XP by simply compiling the source code for the platform you want. Qt is the basis for the KDE desktop environment, and is also used in numerous commercial applications such as Google Earth, Skype for Linux, and Adobe Photoshop Elements.
XView (X Window-System-based Visual/Integrated Environment for Workstations) is a user-interface toolkit to support interactive, graphics-based applications running under the X Window System. XView provides a set of pre-built, user-interface objects such as canvases, scrollbars, menus, and control panels. The appearance and functionality of these objects follow the OPEN LOOK Graphical User Interface (GUI) specification. XView features an object-oriented style Application Programmer's Interface (API) that is straightforward and easy to learn.