Clean up AgPreferences template

src/resources/ui/ag-preferences.ui

@@ -14,7 +14,7 @@
     <property name="can_focus">False</property>
     <property name="type_hint">normal</property>
     <child internal-child="vbox">
-      <object class="GtkBox" id="dialog-vbox1">
+      <object class="GtkBox">
         <property name="can_focus">False</property>
         <property name="orientation">vertical</property>
         <property name="spacing">2</property>
@@ -37,7 +37,7 @@
           </packing>
         </child>
         <child>
-          <object class="GtkGrid" id="grid2">
+          <object class="GtkGrid">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
             <child>
@@ -86,7 +86,7 @@
               </packing>
             </child>
             <child>
-              <object class="GtkLabel" id="label1">
+              <object class="GtkLabel">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="label" translatable="yes">Default house system</property>
@@ -99,7 +99,7 @@
             <child>
               <object class="GtkComboBox" id="house_system">
                 <property name="visible">True</property>
-                <property name="can_focus">False</property>
+                <property name="can_focus">True</property>
                 <property name="model">house_system_model</property>
                 <property name="id_column">0</property>
               </object>