some fixes and improvements

resources/history_dialog.ui

@@ -2,7 +2,6 @@
 <interface>
   <requires lib="gtk+" version="3.12"/>
   <template class="PamacHistoryDialog" parent="GtkDialog">
-    <property name="can_focus">False</property>
     <property name="border_width">6</property>
     <property name="title" translatable="yes">Pamac History</property>
     <property name="default_width">600</property>
@@ -25,7 +24,6 @@
                 <property name="visible">True</property>
                 <property name="can_focus">True</property>
                 <property name="has_focus">True</property>
-                <property name="receives_default">True</property>
               </object>
               <packing>
                 <property name="expand">False</property>