From 84250bbf8860de5930baf946cdde1768d1a726fa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20Dre=C3=9Fler?= <verdre@v0yd.nl>
Date: Sun, 6 May 2018 17:17:33 +0200
Subject: [PATCH] altTab: Don't return from _init() if there are no
 windows/apps

If a new SwitcherPopup is created and there are no windows or apps to
switch through found, instead of returning from _init(), still
initialize the SwitcherPopup and let the check in SwitcherPopup.show()
return false to terminate the popup.

In both cases, with or without the return statements,
WindowManager._startSwitcher() will call SwicherPopup.destroy(), which
will try to disconnect signal handlers, destroy actors etc. Now if the
constructor can't finish creating the popup, some of the functions
called from _onDestroy() will fail and throw errors.

One of those cases is when window-switcher is limited to the current
workspace, and a WindowCyclerPopup is initiated on an empty workspace.
Because this._highlight hasn't been created, _onDestroy() will fail when
trying to destroy the actor of this._highlight.

Also, the actor of this._switcherList will not get destroyed in case
show() returns because this._items is empty. For example, this will
happen when a new AppSwitcherPopup is initialized with at least 1
running app, but 0 windows on the active workspace.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/168
---
 js/ui/altTab.js        | 9 ---------
 js/ui/switcherPopup.js | 5 +++++
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/js/ui/altTab.js b/js/ui/altTab.js
index 1e4cbc453..06b8d7974 100644
--- a/js/ui/altTab.js
+++ b/js/ui/altTab.js
@@ -64,9 +64,6 @@ class AppSwitcherPopup extends SwitcherPopup.SwitcherPopup {
 
         let apps = Shell.AppSystem.get_default().get_running();
 
-        if (apps.length == 0)
-            return;
-
         this._switcherList = new AppSwitcher(apps, this);
         this._items = this._switcherList.icons;
     }
@@ -481,9 +478,6 @@ var CyclerPopup = GObject.registerClass({
 
         this._items = this._getWindows();
 
-        if (this._items.length == 0)
-            return;
-
         this._highlight = new CyclerHighlight();
         global.window_group.add_actor(this._highlight);
 
@@ -559,9 +553,6 @@ class WindowSwitcherPopup extends SwitcherPopup.SwitcherPopup {
 
         let windows = this._getWindowList();
 
-        if (windows.length == 0)
-            return;
-
         let mode = this._settings.get_enum('app-icon-mode');
         this._switcherList = new WindowSwitcher(windows, mode);
         this._items = this._switcherList.icons;
diff --git a/js/ui/switcherPopup.js b/js/ui/switcherPopup.js
index 945f4020a..d1322106e 100644
--- a/js/ui/switcherPopup.js
+++ b/js/ui/switcherPopup.js
@@ -330,6 +330,11 @@ var SwitcherPopup = GObject.registerClass({
             GLib.source_remove(this._initialDelayTimeoutId);
         if (this._noModsTimeoutId != 0)
             GLib.source_remove(this._noModsTimeoutId);
+
+        // Make sure the SwitcherList is always destroyed, it may not be
+        // a child of the actor at this point.
+        if (this._switcherList)
+            this._switcherList.destroy();
     }
 
     _select(num) {