I find myself in the nasty situation that my game tools need to support Mac OSX and I can't demand Windows only. The good news is that I don't have to port any tools -- this is a ground up write that can take both platforms into account ahead of time. I'm free to choose any language I like, but an attempt with Python and wxWidgets convinced me that it wasn't a path I want to follow. Right now I would very much like to use C# for all my tool stuff and just build it in a way that works well across Windows, OSX, and potentially Linux.
I already know that Mono's runtime works well enough for my purposes, so I'm not concerned about that. I'm also not concerned with rendering. The big question is what to do about the UI library. I want to build fairly complex interfaces, and I only want to do it once. That tends to suggest either WinForms or Gtk#, but I don't know how well WinForms works on OSX or how well Gtk# works in general. I'm hoping one of you has "in the trenches" experience on doing cross platform C# interfaces and some recommendations about how to do this.
Edited by Promit, 20 February 2013 - 03:55 PM.