One problem is that they are still on Gtk 2.x. There is so much work that was done in 3.x over the last 7 years that improves things.
Visual Studio for Mac is also Gtk 2.x, but they (Xamarin at the time) invested heavily in a custom Gtk fork as much of the hacks were not suitable upstream.
Visual Studio for Mac is also Gtk 2.x, but they (Xamarin at the time) invested heavily in a custom Gtk fork as much of the hacks were not suitable upstream.