[gnome-klotski] Go around GTK+ bug 744531.

[Arnaud Bonatti <arnaudb src gnome org>]

commit f2beac8a43df5b6d292aa5bf056bf2763f7794e4
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Sun Feb 14 07:49:15 2016 +0100

    Go around GTK+ bug 744531.

 data/klotski.css |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)
---
diff --git a/data/klotski.css b/data/klotski.css
index 2fef593..88a558b 100644
--- a/data/klotski.css
+++ b/data/klotski.css
@@ -35,3 +35,8 @@ treeview.toggle-like-pixbuf:disabled {
 treeview.toggle-like-pixbuf:disabled:checked {
   -gtk-icon-source: -gtk-icontheme("gtk-yes");  /* TODO maybe deprecated */
 }
+
+/* https://bugzilla.gnome.org/show_bug.cgi?id=744531 */
+button.flat:insensitive {
+  color: @theme_unfocused_bg_color;
+}