From TDN

I finally got all radiant files together and attempted to do a test build. Everything went exactly as described with the aboutmsg.h error message so I added it to the project and I still get the same 2 error messages referencing it.

gtkdlgs.cpp(41) : fatal error C1083: Cannot open include file: 'aboutmsg.h': No such file or directory

and...

console.cpp(39) : fatal error C1083: Cannot open include file: 'aboutmsg.h': No such file or directory

The file is in the include dir, but it apparantly still isn't visible.