Use action instead of on_nickname_pressed function

briar-gtk/briar_gtk/actions/registration.py

@@ -15,4 +15,11 @@ class RegistrationActions(Actions):
         self._setup_actions()
 
     def _setup_actions(self):
-        pass
+        self._setup_proceed_from_nickname_action()
+
+    def _setup_proceed_from_nickname_action(self):
+        self._setup_action("proceed-from-nickname", None, self._proceed_from_nickname)
+
+    # pylint: disable=unused-argument
+    def _proceed_from_nickname(self, action, parameter):
+        self.widget.proceed_from_nickname()

briar-gtk/briar_gtk/containers/registration.py

@@ -51,10 +51,10 @@ class RegistrationContainer(Container):
 
     # pylint: disable=unused-argument
     def _on_nickname_enter(self, event):
-        self.on_nickname_next_pressed(None)
+        self.proceed_from_nickname()
 
     # pylint: disable=unused-argument
-    def on_nickname_next_pressed(self, button):
+    def proceed_from_nickname(self):
         nickname_error_label = self.builder.get_object("nickname_error_label")
         if self._nickname_is_empty():
             nickname_error_label.show()

briar-gtk/data/ui/registration.ui

@@ -230,7 +230,7 @@
             <property name="use_underline">True</property>
             <property name="can_focus">True</property>
             <property name="label" translatable="yes">Next</property>
-            <signal name="clicked" handler="on_nickname_next_pressed"/>
+            <property name="action_name" translatable="yes">registration.proceed-from-nickname</property>
             <style>
               <class name="suggested-action"/>
             </style>