Xwt is a cross-platform UI toolkit for creating desktop applications with .NET and Mono. This package contains the GTK toolkit backend for Xwt based applications targeting GTK2 on Mac. Xwt.Gtk requires gtk-sharp (https://github.com/mono/gtk-sharp/). The Windows installation package can be obtained from http://www.monodevelop.com/download/#win.
$ dotnet add package Xwt.Gtk.MacNo README available.