make[3]: Entering directory '/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample/test'
/usr/bin/mcs -out:WidgetViewer.exe -r:../../glib/glib-sharp.dll -r:../../pango/pango-sharp.dll -r:../../atk/atk-sharp.dll -r:../../gdk/gdk-sharp.dll -r:../../gtk/gtk-sharp.dll ./TestCheckButton.cs ./TestColorSelection.cs ./TestRadioButton.cs ./TestRange.cs ./TestStatusbar.cs ./TestDialog.cs ./TestFlipping.cs ./TestSizeGroup.cs ./TestCombo.cs ./TestComboBox.cs ./WidgetViewer.cs
./TestCombo.cs(17,14): warning CS0612: `Gtk.Combo' is obsolete
./TestRange.cs(35,6): error CS0104: `Range' is an ambiguous reference between `System.Range' and `Gtk.Range'
/usr/lib64/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample/test/../../gtk/gtk-sharp.dll (Location of the symbol related to previous error)
./TestRange.cs(35,13): error CS0030: Cannot convert type `Gtk.HScale' to `System.Range'
./TestRange.cs(42,6): error CS0104: `Range' is an ambiguous reference between `System.Range' and `Gtk.Range'
/usr/lib64/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample/test/../../gtk/gtk-sharp.dll (Location of the symbol related to previous error)
./TestRange.cs(42,13): error CS0030: Cannot convert type `Gtk.HScrollbar' to `System.Range'
./TestRange.cs(62,6): error CS0104: `Range' is an ambiguous reference between `System.Range' and `Gtk.Range'
/usr/lib64/mono/4.5/mscorlib.dll (Location of the symbol related to previous error)
/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample/test/../../gtk/gtk-sharp.dll (Location of the symbol related to previous error)
./TestRange.cs(62,13): error CS0030: Cannot convert type `Gtk.VScale' to `System.Range'
./TestCombo.cs(31,20): warning CS0612: `Gtk.Combo' is obsolete
Compilation failed: 6 error(s), 2 warnings
make[3]: *** [Makefile:504: WidgetViewer.exe] Error 1
make[3]: Leaving directory '/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample/test'
make[2]: *** [Makefile:439: all-recursive] Error 1
make[2]: Leaving directory '/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21/sample'
make[1]: *** [Makefile:454: all-recursive] Error 1
make[1]: Leaving directory '/var/tmp/portage/dev-dotnet/gtk-sharp-2.12.21/work/gtk-sharp-2.12.21'
make: *** [Makefile:382: all] Error 2

• ERROR: dev-dotnet/gtk-sharp-2.12.21::lang-kit failed (compile phase):
• emake failed

(note: mono was just installed prior to this, the current version from portage dev-lang/mono 6.12.0.122)