[gnome-mahjongg/arnaudb/wip/gtk4: 28/41] Adapt to MenuButton API.

[Arnaud B. <arnaudb src gnome org>]

commit 13fc22473ac52fb69da9ff35ed2f7f855cda1326
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Fri Mar 27 19:06:55 2020 +0100

    Adapt to MenuButton API.

 src/gnome-mahjongg.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gnome-mahjongg.vala b/src/gnome-mahjongg.vala
index 45c0343..46e8e6f 100644
--- a/src/gnome-mahjongg.vala
+++ b/src/gnome-mahjongg.vala
@@ -157,7 +157,7 @@ public class Mahjongg : Gtk.Application
         var menu_button = new Gtk.MenuButton ();
         menu_button.valign = Gtk.Align.CENTER;
         menu_button.set_menu_model (menu);
-        menu_button.set_image (new Gtk.Image.from_icon_name ("open-menu-symbolic", Gtk.IconSize.BUTTON));
+        menu_button.set_icon_name ("open-menu-symbolic");
 
         var header_bar = new Gtk.HeaderBar ();
         header_bar.set_custom_title (title_box);