Add basic functions of roster filtering

src/roster_window.py

@@ -4165,8 +4165,13 @@ class RosterWindow:
         if self.hpaned.get_child2() is not None:
             self.show_roster_vbox(widget.get_active())
 
-#    def on_show_roster_filter_menuitem_toggled(self, widget):
-#        """ Show the roster filter textentry """
+    def on_roster_filter_entry_insert_at_cursor(self, widget):
+        """ When we update the content of the filter """
+        pass
+
+    def on_show_roster_filter_menuitem_toggled(self, widget):
+        """ Show the roster filter entry """
+        pass
 
     def on_roster_hpaned_notify(self, pane, gparamspec):
         """