[gnome-shell/gnome-3-28] altSwitcher: Fix error when all alternatives are disabled

[Florian Müllner <fmuellner src gnome org>]

commit a73294312f9a16f0722148dc5b26f5666feb5119
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Nov 16 11:39:08 2018 +0100

    altSwitcher: Fix error when all alternatives are disabled
    
    While we do consider the case that we don't have a child to show for the
    visibility, we are still trying to move the click action unconditionally.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/783
    
    (cherry picked from commit e77463b875311ff35bb94daadf2d96cb1886e2c1)

 js/ui/status/system.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/js/ui/status/system.js b/js/ui/status/system.js
index 68a0b4b5b..cd6f3d8b0 100644
--- a/js/ui/status/system.js
+++ b/js/ui/status/system.js
@@ -58,6 +58,9 @@ var AltSwitcher = new Lang.Class({
             childToShow = this._standard;
         } else if (this._alternate.visible) {
             childToShow = this._alternate;
+        } else {
+            this.actor.hide();
+            return;
         }
 
         let childShown = this.actor.get_child();
@@ -79,7 +82,7 @@ var AltSwitcher = new Lang.Class({
             global.sync_pointer();
         }
 
-        this.actor.visible = (childToShow != null);
+        this.actor.show();
     },
 
     _onDestroy() {