[gnome-control-center] printers: Wrap GtkListBox inside a GtkBox

[Felipe Borges <felipeborges src gnome org>]

commit 6a6f4b71d9b60ccdddab499a0547865de215e0ca
Author: Felipe Borges <felipeborges gnome org>
Date:   Thu Aug 24 12:41:35 2017 +0200

    printers: Wrap GtkListBox inside a GtkBox
    
    In order to vertically align the printers panel content by the
    same standards as the other panels, we should set the GtkListBox
    top and bottom margins to 32px.
    
    This commit wraps GtkListBox inside a GtkBox to handle the Gtk+
    issues discussed in Bug 773459 regarding the background of ListBox
    margins.
    
    This commit can be cleanly reverted once the issue is fixed in
    Gtk+.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786384

 panels/printers/printers.ui |   17 +++++++++++------
 1 files changed, 11 insertions(+), 6 deletions(-)
---
diff --git a/panels/printers/printers.ui b/panels/printers/printers.ui
index 31298f5..376c3f1 100644
--- a/panels/printers/printers.ui
+++ b/panels/printers/printers.ui
@@ -132,13 +132,18 @@
             <property name="min-content-height">490</property>
             <property name="vexpand">True</property>
             <child>
-              <object class="GtkListBox" id="content">
+              <object class="GtkBox">
                 <property name="visible">True</property>
-                <property name="can_focus">True</property>
-                <property name="selection-mode">GTK_SELECTION_NONE</property>
-                <style>
-                  <class name="background"/>
-                </style>
+                <child>
+                  <object class="GtkListBox" id="content">
+                    <property name="visible">True</property>
+                    <property name="can_focus">True</property>
+                    <property name="selection-mode">GTK_SELECTION_NONE</property>
+                    <style>
+                      <class name="background"/>
+                    </style>
+                  </object>
+                </child>
               </object>
             </child>
           </object>