We have a proprietary macro language in one of our products, edited through our Windows software. I would like to add intellisense, but I have no idea how to go about this (at least not without completely reinventing the wheel). Is there any sample code or 3rd party package that can at least get me started? It doesn't have to be free.
The application uses .NET, written in C#.
There are various options listed at http://channel9.msdn.com/forums/TechOff/210185-Advice-on-implementing-Intellisense-in-my-application/
There is a CodeProject article about adding intellisense to your own applications: DIY Intellisense
It should give you a good start.
There are also open source packages that you can dig into if you really want dig deep into an implementation: #develop (short for SharpDevelop) is a free IDE for C#, VB.NET and Boo projects