The ANSI Screen Editor is a basic editor for oldschool colored ANSI screens originally released by Zeta Centauri at http://zetacentauri.com and downloaded more than 8000 times before being open-sourced.
A prebuilt installer is available in the installer directory here:
It is written using C# .NET 3.5. The included project is a Visual Studio 2012 project, but there's nothing about the code that would prevent you from creating and using an older Visual Studio project.
This program does not work using Mono on Linux due to this bug: https://bugzilla.novell.com/show_bug.cgi?id=593951
This project is licensed under the MIT License.
I consider this to be completed software and it is no longer being actively developed. I am willing to accept pull requests if you have improvements to contribute.