[gtk+] Revert "window: Reinstate logic for should_use_csd()"

[Emmanuele Bassi <ebassi src gnome org>]

commit 9590879e2f550a29d230099680081a9d3a90d414
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Jun 18 16:10:36 2015 +0100

    Revert "window: Reinstate logic for should_use_csd()"
    
    This reverts commit f043fd532dc66a7abb1d4ea57c666655330cc429.
    
    The whole point of having can_use_csd() return TRUE when GTK_CSD is
    unset is to use it inside enable_csd().
    
    https://bugzilla.gnome.org/show_bug.cgi?id=751140

 gtk/gtkwindow.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 7f4e74b..fb8e0b0 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4079,7 +4079,8 @@ gtk_window_can_use_csd (GtkWindow *window)
 
   csd_env = g_getenv ("GTK_CSD");
 
-  return (g_strcmp0 (csd_env, "1") == 0);
+  /* If GTK_CSD is unset we default to CSD support */
+  return csd_env == NULL || (strcmp (csd_env, "1") == 0);
 }
 
 static void