[gnome-shell/wip/exalm/gestures2: 30/33] workspaceAnimation: Use window clones

[Alexander Mikhaylenko <alexm src gnome org>]

commit 56bf7462f325157dab093d54de16275afb90ab7e
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Thu Jul 4 23:15:15 2019 +0500

    workspaceAnimation: Use window clones
    
    Instead of reparenting windows, clone them. This will allow to properly
    support multi-monitor setups in subsequent commits.
    
    Block window mapping animation while the animation is running to prevent
    new windows appearing during the animation from being visible at the same
    time as their clones.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/issues/929
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1326

 js/ui/workspaceAnimation.js | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)
---
diff --git a/js/ui/workspaceAnimation.js b/js/ui/workspaceAnimation.js
index 3687867551..67c2e8083a 100644
--- a/js/ui/workspaceAnimation.js
+++ b/js/ui/workspaceAnimation.js
@@ -48,16 +48,19 @@ class WorkspaceGroup extends Clutter.Actor {
             this._shouldShowWindow(w.meta_window));
 
         for (let window of windows) {
-            let record = {
-                window,
-                parent: window.get_parent(),
-            };
+            let clone = new Clutter.Clone({
+                source: window,
+                x: window.x,
+                y: window.y,
+            });
 
-            record.parent.remove_child(window);
-            this.add_child(window);
-            window.show();
+            this.add_child(clone);
+            window.hide();
+
+            let record = { window, clone };
 
             record.windowDestroyId = window.connect('destroy', () => {
+                clone.destroy();
                 this._windows.splice(this._windows.indexOf(record), 1);
             });
 
@@ -68,11 +71,10 @@ class WorkspaceGroup extends Clutter.Actor {
     _removeWindows() {
         for (const record of this._windows) {
             record.window.disconnect(record.windowDestroyId);
-            this.remove_child(record.window);
-            record.parent.add_child(record.window);
+            record.clone.destroy();
 
-            if (!record.window.get_meta_window().get_workspace().active)
-                record.window.hide();
+            if (record.window.get_meta_window().get_workspace().active)
+                record.window.show();
         }
 
         this._windows = [];