[gnome-shell] windowManager: Animate the appearance of new windows after overview closes

[Marge Bot <marge-bot src gnome org>]

commit 88b2c9a046170d150e41f929810b8fa9f5198ca6
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Thu Sep 17 15:25:49 2020 +0800

    windowManager: Animate the appearance of new windows after overview closes
    
    So that the animation doesn't get skipped if the overview is visible but
    in the process of closing.
    
    In this case the overview being visible also means that it is closing,
    because if it's visible and not already closing then `_shouldAnimateActor`
    would have returned false and exited `_mapWindow` earlier.
    
    Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/1814,
           https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3242
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1440>

 js/ui/windowManager.js | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index 2ded682362..48fa9a5934 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -1446,7 +1446,19 @@ var WindowManager = class {
         dimmer.setDimmed(false, this._shouldAnimate());
     }
 
-    _mapWindow(shellwm, actor) {
+    _waitForOverviewToHide() {
+        if (!Main.overview.visible)
+            return Promise.resolve();
+
+        return new Promise(resolve => {
+            const id = Main.overview.connect('hidden', () => {
+                Main.overview.disconnect(id);
+                resolve();
+            });
+        });
+    }
+
+    async _mapWindow(shellwm, actor) {
         actor._windowType = actor.meta_window.get_window_type();
         actor._notifyWindowTypeSignalId =
             actor.meta_window.connect('notify::window-type', () => {
@@ -1488,6 +1500,7 @@ var WindowManager = class {
             actor.show();
             this._mapping.add(actor);
 
+            await this._waitForOverviewToHide();
             actor.ease({
                 opacity: 255,
                 scale_x: 1,
@@ -1505,6 +1518,7 @@ var WindowManager = class {
             actor.show();
             this._mapping.add(actor);
 
+            await this._waitForOverviewToHide();
             actor.ease({
                 opacity: 255,
                 scale_x: 1,