https://github.com/mono/gtk-sharp/commit/a00552ad68ae349e89e440dca21b86dbd6bccd30
https://bugs.gentoo.org/697108
--- a/sample/test/TestRange.cs	2012-09-25 14:19:02.000000000 -0700
+++ b/sample/test/TestRange.cs	2020-07-05 09:07:25.112932811 -0700
@@ -10,6 +10,10 @@
 
 using Gtk;
 
+// disambiguate, Gtk.Range vs System.Range
+using Range=Gtk.Range;
+
+
 namespace WidgetViewer {
 
 	public class TestRange