re-introduce padding on language selection screen

and simplify it a bit while we're here.

subiquity/ui/views/welcome.py

@@ -19,10 +19,10 @@ Welcome provides user with language selection
 
 """
 import logging
-from urwid import BoxAdapter, Text
+from urwid import Text
 from subiquitycore.ui.lists import SimpleList
 from subiquitycore.ui.buttons import menu_btn
-from subiquitycore.ui.container import ListBox
+from subiquitycore.ui.container import Pile
 from subiquitycore.ui.utils import Padding
 from subiquitycore.view import BaseView
 
@@ -34,15 +34,18 @@ class WelcomeView(BaseView):
     def __init__(self, model, controller):
         self.model = model
         self.controller = controller
-        super().__init__(ListBox([
-            Padding.center_50(self._build_model_inputs())]))
+        super().__init__(Pile([
+            ('pack', Text("")),
+            Padding.center_50(self._build_model_inputs()),
+            ('pack', Text("")),
+            ]))
 
     def _build_model_inputs(self):
         sl = []
         for code, label, native in self.model.get_languages():
             sl.append(menu_btn(label=native, on_press=self.confirm, user_arg=code))
 
-        return BoxAdapter(SimpleList(sl), height=len(sl))
+        return SimpleList(sl)
 
     def confirm(self, sender, code):
         self.model.switch_language(code)