[gnome-tetravex/arnaudb/wip/gtk4] Fix add_controller.

[Arnaud B. <arnaudb src gnome org>]

commit 9e0c3e30f007bb5062aaa136bc21d547212aeb6c
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Mon Apr 6 17:21:40 2020 +0200

    Fix add_controller.

 src/gnome-tetravex.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gnome-tetravex.vala b/src/gnome-tetravex.vala
index 183c46b..518e228 100644
--- a/src/gnome-tetravex.vala
+++ b/src/gnome-tetravex.vala
@@ -306,7 +306,7 @@ private class Tetravex : Gtk.Application
         this.add_window (window);
         key_controller = new EventControllerKey ();
         key_controller.key_pressed.connect (on_key_pressed);
-        window.add_controller (key_controller);
+        ((Widget) window).add_controller (key_controller);
         window.size_allocate.connect (on_size_allocate);
         window.map.connect (init_state_watcher);
         window.set_default_size (settings.get_int ("window-width"), settings.get_int ("window-height"));