put (group)chat controls in a hbox to be more extensible

data/gui/chat_control.ui

@@ -2,6 +2,10 @@
 <interface>
   <requires lib="gtk+" version="2.16"/>
   <!-- interface-naming-policy project-wide -->
+  <object class="GtkHBox" id="chat_control_hbox">
+    <property name="can_focus">True</property>
+    <property name="spacing">1</property>
+    <child>
       <object class="GtkVBox" id="chat_control_vbox">
         <property name="can_focus">True</property>
         <property name="border_width">3</property>
@@ -667,6 +671,11 @@ audio-mic-volume-low</property>
           </packing>
         </child>
       </object>
+      <packing>
+        <property name="position">0</property>
+      </packing>
+    </child>
+  </object>
   <object class="GtkAdjustment" id="adjustment2">
     <property name="upper">110</property>
     <property name="step_increment">1</property>

data/gui/groupchat_control.ui

@@ -2,6 +2,9 @@
 <interface>
   <requires lib="gtk+" version="2.16"/>
   <!-- interface-naming-policy project-wide -->
+  <object class="GtkHBox" id="groupchat_control_hbox">
+    <property name="can_focus">True</property>
+    <child>
       <object class="GtkVBox" id="groupchat_control_vbox">
         <property name="can_focus">True</property>
         <property name="border_width">3</property>
@@ -435,4 +438,9 @@
           </packing>
         </child>
       </object>
+      <packing>
+        <property name="position">0</property>
+      </packing>
+    </child>
+  </object>
 </interface>

src/message_control.py

@@ -62,7 +62,7 @@ class MessageControl(object):
         gajim.last_message_time[self.account][self.get_full_jid()] = 0
 
         self.xml = gtkgui_helpers.get_gtk_builder('%s.ui' % widget_name)
-        self.widget = self.xml.get_object('%s_vbox' % widget_name)
+        self.widget = self.xml.get_object('%s_hbox' % widget_name)
 
     def get_full_jid(self):
         fjid = self.contact.jid