Restore opacity peeking window different workspace

panel.js

@@ -1325,7 +1325,7 @@ var Panel = GObject.registerClass({
                     transition: 'easeOutQuad'
                 };
 
-                Utils.animateWindowOpacity(w.get_compositor_private(), tweenOpts);
+                Utils.animateWindowOpacity(w.get_compositor_private(), tweenOpts, true);
             }
         });
     }

utils.js

@@ -420,7 +420,7 @@ var activateSiblingWindow = function(windows, direction, startWindow) {
     }
 };
 
-var animateWindowOpacity = function(window, tweenOpts) {
+var animateWindowOpacity = function(window, tweenOpts, adjustVisibility) {
     //there currently is a mutter bug with the windowactor opacity, starting with 3.34
     //https://gitlab.gnome.org/GNOME/mutter/issues/836
 
@@ -433,7 +433,7 @@ var animateWindowOpacity = function(window, tweenOpts) {
 
         window = windowActor.get_first_child() || windowActor;
 
-        if (!windowActor.visible && visible) {
+        if (!windowActor.visible && visible && adjustVisibility) {
             window.opacity = 0;
             windowActor.visible = visible;
         }

windowPreview.js

@@ -590,6 +590,11 @@ var PreviewMenu = GObject.registerClass({
         let focusWindow = () => this._focusMetaWindow(Me.settings.get_int('peek-mode-opacity'), window);
 
         this._restorePeekedWindowStack();
+
+        if (this._peekedWindow && windowWorkspace != currentWorkspace) {
+            currentWorkspace.list_windows().forEach(mw => this.animateWindowOpacity(mw, null, 255))
+        }
+
         this._peekedWindow = window;
 
         if (currentWorkspace != windowWorkspace) {
@@ -650,20 +655,26 @@ var PreviewMenu = GObject.registerClass({
                 if (isFocused && mw.minimized) {
                     wa.show();
                 }
-
-                if (!mw.minimized) {
-                    let tweenOpts = getTweenOpts({ opacity: isFocused ? 255 : dimOpacity });
-
-                    if (immediate && !mw.is_on_all_workspaces()) {
-                        tweenOpts.time = 0;
-                    }
-
-                    Utils.animateWindowOpacity(wa, tweenOpts);
-                }
+
+                this.animateWindowOpacity(mw, wa, isFocused ? 255 : dimOpacity, immediate)
             }
         });
     }
 
+    animateWindowOpacity(metaWindow, windowActor, opacity, immediate) {
+        windowActor = windowActor || metaWindow.get_compositor_private();
+
+        if (windowActor && !metaWindow.minimized) {
+            let tweenOpts = getTweenOpts({ opacity });
+
+            if (immediate && !metaWindow.is_on_all_workspaces()) {
+                tweenOpts.time = 0;
+            }
+
+            Utils.animateWindowOpacity(windowActor, tweenOpts);
+        }
+    }
+
     _restorePeekedWindowStack() {
         let windowActor = this._peekedWindow ? this._peekedWindow.get_compositor_private() : null;