[simple-scan] Don't use headerbar on i3 desktop

[Robert Ancell <rancell src gnome org>]

commit 0987fb8f5037ad8f165b628be48f257e1c6ba4de
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu Jun 22 09:25:17 2017 +1200

    Don't use headerbar on i3 desktop
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784048

 src/app-window.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/app-window.vala b/src/app-window.vala
index e760a48..1fb207d 100644
--- a/src/app-window.vala
+++ b/src/app-window.vala
@@ -1696,7 +1696,7 @@ public class AppWindow : Gtk.ApplicationWindow
 
     private bool is_traditional_desktop ()
     {
-        const string[] traditional_desktops = { "Unity", "XFCE", "MATE", "LXDE", "Cinnamon", "X-Cinnamon" };
+        const string[] traditional_desktops = { "Unity", "XFCE", "MATE", "LXDE", "Cinnamon", "X-Cinnamon", 
"i3" };
         foreach (var name in traditional_desktops)
             if (is_desktop (name))
                 return true;