Implement monospace property on TextView

This partially addresses #7 however a more complete solution
(allowing setting of an arbitrary font on the widget,) requires
the implementation of gtk_widget_set_font_map and all the
attendant Pango bizness.

examples/07_text.p6

@@ -8,12 +8,17 @@ my $editable    = GTK::Simple::CheckButton.new(label => 'Editable');
 $editable.status = True;
 my $show-cursor = GTK::Simple::CheckButton.new(label => 'Show Cursor');
 $show-cursor.status = True;
+
+my $monospace = GTK::Simple::CheckButton.new(label => 'Monospaced');
+$monospace.status = False;
+
 my $text-view   = GTK::Simple::TextView.new;
 
 $editable.toggled.tap(-> $w { $text-view.editable = $w.status });
 $show-cursor.toggled.tap( -> $w { $text-view.cursor-visible = $w.status });
+$monospace.toggled.tap( -> $w { $text-view.monospace = $w.status });
 
-my $vbox = GTK::Simple::VBox.new($editable, $show-cursor, $text-view);
+my $vbox = GTK::Simple::VBox.new($editable, $show-cursor, $monospace, $text-view);
 
 $app.set_content($vbox);
 

lib/GTK/Simple.pm6

@@ -756,6 +756,21 @@ class GTK::Simple::TextView does GTK::Simple::Widget {
         is gtk-property(&gtk_text_view_get_cursor_visible, &gtk_text_view_set_cursor_visible)
         { * }
 
+
+    sub gtk_text_view_get_monospace(GtkWidget $widget)
+        is native(&gtk-lib)
+        returns int32
+        { * }
+
+    sub gtk_text_view_set_monospace(GtkWidget $widget, int32 $setting)
+        is native(&gtk-lib)
+        { * }
+
+    method monospace()
+        returns Bool
+        is gtk-property(&gtk_text_view_get_monospace, &gtk_text_view_set_monospace)
+        { * }
+
 }
 
 class GTK::Simple::Button does GTK::Simple::Widget {