overview: Delay showing until there is gesture progress

Currently swiping down in the session enters the overview, but
as there is no progress (clamped to 0 from negative), the only
visible effect is that the top bar transitions to transparent.

Avoid this glitch by delaying showing the overview until there
is some non-0 progress.

Closes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/7456
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/3777>
(cherry picked from commit fb30a94243c3ced887a8ccadb2987c27d61bf467)

diff --git a/js/ui/overview.js b/js/ui/overview.js
index 88898bd631616873ed2f29d0d45af967c0167c2a..cb0bf22f364a97719aabd2a38624c3b81381bc54 100644 (file)
--- a/js/ui/overview.js
+++ b/js/ui/overview.js
@@ -358,6 +358,9 @@ export class Overview extends Signals.EventEmitter {
     }
 
     _gestureUpdate(tracker, progress) {
+        if (progress === 0)
+            return;
+
         if (!this._shown) {
             this._shown = true;
             this._visible = true;