Just in case you were using (now unmaintained?) GtkSharp, their direct "successor" and replacement is Gir.Core which is actively maintained and lets you target

Just in case you were using (now unmaintained?) GtkSharp, their direct "successor" and replacement is Gir.Core which is actively maintained and lets you target latest GObject APIs: https://github.com/gircore/gir.core https://github.com/gircore/gir.core