David Baldwin wrote Dialog Design. It was originally a Shareware tool. Later he made it freeware given that most developers (and he!) had moved on to tools that run under Microsoft Windows. At my (David O'Shea) request, he has made it Open Source. He would probably prefer that you do not contact him regarding the tool.
I (David O'Shea) asked David Baldwin to release the code as Open Source and he kindly complied. He sent me the source so I could get it to compile and document how to. I will provide whatever support I can for the source code although I'm not at all familiar with it yet!
Obviously you can run the tool under MS-DOS to produce code for dialogs that use Turbo Vision with Borland's Pascal and C compilers. The source code will compile with Borland Pascal 7. Perhaps it would compile with Virtual Pascal, Free Pascal Compiler, etc., if you have Borland's Turbo Vision source (which you should have if you purchased Borland Pascal 7 or purchased the Run-Time Library (RTL) source code separately).
Please let me know (post in the forums) regarding which of these is important to you so I know what to work on, or if there is something else you'd like done with the code.