Simplify disabling tiling shortcuts (#828)

Co-authored-by: Danielle Foré <danielle@elementary.io>

Author: lenemter

compositor/WindowManager.vala

@@ -59,8 +59,6 @@ namespace GreeterCompositor {
 
             show_stage ();
 
-            disable_tiling_shortcuts ();
-
             fade_in_screen.save_easing_state ();
             fade_in_screen.set_easing_duration (1000);
             fade_in_screen.set_easing_mode (Clutter.AnimationMode.EASE);
@@ -73,16 +71,6 @@ namespace GreeterCompositor {
             });
         }
 
-        private void disable_tiling_shortcuts () {
-            var mutter_settings = new GLib.Settings ("org.gnome.mutter.keybindings");
-            mutter_settings.set_strv ("toggle-tiled-left", {});
-            mutter_settings.set_strv ("toggle-tiled-right", {});
-
-            var wm_settings = new GLib.Settings ("org.gnome.desktop.wm.keybindings");
-            wm_settings.set_strv ("minimize", {});
-            wm_settings.set_strv ("toggle-maximized", {});
-        }
-
         void refresh_background () {
             unowned Meta.Display display = get_display ();
 
@@ -188,6 +176,11 @@ namespace GreeterCompositor {
 
             KeyBinding.set_custom_handler ("show-desktop", () => {});
 
+            KeyBinding.set_custom_handler ("toggle-tiled-left", () => {});
+            KeyBinding.set_custom_handler ("toggle-tiled-right", () => {});
+            KeyBinding.set_custom_handler ("minimize", () => {});
+            KeyBinding.set_custom_handler ("toggle-maximized", () => {});
+
             zoom = new Zoom (this);
 
             /* orca (screenreader) doesn't listen to it's