brent would WinForms be in that stuff?
When I retired, and was no longer developing Windows software using C#, I became interested in Mono, hoping to be able to continue using that language to write Linux utilities. I tried using Mono many times over the years, but the capabilities of that program never changed: Winforms were not part of what Microsoft released as freeware.
It was possible to use Mono to write terminal apps, or to use the Linux toolkits, but not to write programs that were based on Winforms. That was Microsoft's toolkit, and not ported to Linux.
I haven't checked recently, but unless that policy has been changed - and I doubt that - it is still in effect.