diff -Nur gnome-shell_3.35.91-1ubuntu2/js/gdm/loginDialog.js gnome-shell_3.35.91-1ubuntu2vv2/js/gdm/loginDialog.js
--- gnome-shell_3.35.91-1ubuntu2/js/gdm/loginDialog.js	2020-02-18 07:15:42.000000000 +0800
+++ gnome-shell_3.35.91-1ubuntu2vv2/js/gdm/loginDialog.js	2020-03-17 18:53:11.667577976 +0800
@@ -1255,7 +1255,11 @@
                                         { sortGroup: CtrlAltTab.SortGroup.MIDDLE });
         this.activate();
 
-        this.opacity = 0;
+        // Clutter doesn't yet fully support invisible parents with forced
+        // visible children and will make everything invisible (flicker) on
+        // the first frame if we start at 0. So we start at 1 instead...
+        this.opacity = 1;
+        this._logoBin.set_opacity_override(255);
 
         Main.pushModal(this, { actionMode: Shell.ActionMode.LOGIN_SCREEN });
 
@@ -1263,6 +1267,7 @@
             opacity: 255,
             duration: 1000,
             mode: Clutter.AnimationMode.EASE_IN_QUAD,
+            onComplete: () => { this._logoBin.set_opacity_override(-1); },
         });
 
         return true;