From 96cd9bb387102c3f1e79b4e531264d853386140a Mon Sep 17 00:00:00 2001
From: jderose9 <coder@derose.io>
Date: Wed, 11 Oct 2017 21:30:03 -0400
Subject: [PATCH] null check for focus_app, fixed #224, #246

---
 windowPreview.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/windowPreview.js b/windowPreview.js
index 05eea99..9f35085 100644
--- a/windowPreview.js
+++ b/windowPreview.js
@@ -199,8 +199,8 @@ const thumbnailPreviewMenu = new Lang.Class({
         this._hoverOpenTimeoutId = null;
         if (!this.isOpen && this._dtpSettings.get_boolean("show-window-previews")) {
             this.popup();          
-            let focusedApp = Shell.WindowTracker.get_default().focus_app.get_name();
-            if (focusedApp === "Oracle VM VirtualBox") {
+            let focusedApp = Shell.WindowTracker.get_default().focus_app;
+            if (focusedApp &&  focusedApp.get_name() === "Oracle VM VirtualBox") {
                 this.actor.grab_key_focus();
             }
         }