[gnome-shell] popupMenu: make sure to break the grab when the slider is not visible

[Stefano Facchini <sfacchini src gnome org>]

commit 3422e1dca76021a2ee98197ba511f6afa6174b38
Author: Stefano Facchini <stefano facchini gmail com>
Date:   Fri Mar 23 19:32:17 2012 +0100

    popupMenu: make sure to break the grab when the slider is not visible
    
    Otherwise the grab will persist for example after closing the PopupMenu
    with Escape.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=672713

 js/ui/popupMenu.js |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/popupMenu.js b/js/ui/popupMenu.js
index ace32e0..09a9b73 100644
--- a/js/ui/popupMenu.js
+++ b/js/ui/popupMenu.js
@@ -546,6 +546,10 @@ const PopupSliderMenuItem = new Lang.Class({
         this._slider.connect('repaint', Lang.bind(this, this._sliderRepaint));
         this.actor.connect('button-press-event', Lang.bind(this, this._startDragging));
         this.actor.connect('scroll-event', Lang.bind(this, this._onScrollEvent));
+        this.actor.connect('notify::mapped', Lang.bind(this, function() {
+            if (!this.actor.mapped)
+                this._endDragging();
+        }));
 
         this._releaseId = this._motionId = 0;
         this._dragging = false;