add sidebar name as well as add handler for clicking the sidebar

src/window.ui

@@ -506,6 +506,7 @@
           <object class="HdyLeaflet" id="stack_2">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
+            <property name="visible_child">sidebar</property>
             <property name="visible_child_name">sidebar</property>
             <property name="mode_transition_type">slide</property>
             <property name="child_transition_type">slide</property>
@@ -515,6 +516,7 @@
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="stack">file_sorting</property>
+                <signal name="button-release-event" handler="sidebar_clicked" swapped="no"/>
               </object>
               <packing>
                 <property name="name">sidebar</property>