Microsoft Business Solutions Great Plains, former Great Plains Software Dynamics and eEnterprise are Dexterity-written applications. Also small business line: Microsoft Small Business Manager or Small Business Financials is written in Dexterity and uses the same code base as Great Plains.
The history of the Dexterity. Great Plains Dexterity - is proprietary programming language and technology, designed back to earlier 1990th with the goal to build platform independent graphical accounting package - Great Plains Dynamics. Dexterity itself is written in C (following popular those days hope - that C will provide platform independence). You can install Dexterity from Great Plains 7.5 CD #2. Obviously it requires a lot of learning / training, but it allows your custom piece be seamlessly integrated with Great Plains interface.