[gnome-calendar] window: fix more styling issues

[Erick Pérez Castellanos <erickpc src gnome org>]

commit 9838c7fa41b1e14d84f3c2650e5a3e4a9de19c7f
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon May 11 10:12:59 2015 -0300

    window: fix more styling issues

 data/ui/window.ui |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/data/ui/window.ui b/data/ui/window.ui
index d342f0e..4d78847 100644
--- a/data/ui/window.ui
+++ b/data/ui/window.ui
@@ -147,6 +147,9 @@
                         <property name="receives_default">True</property>
                         <property name="no_show_all">True</property>
                         <signal name="clicked" handler="undo_remove_action" object="GcalWindow" 
swapped="no"/>
+                        <style>
+                          <class name="text-button"/>
+                        </style>
                       </object>
                       <packing>
                         <property name="left_attach">1</property>