kivy: improve checkbox_dialog layout

gui/kivy/uix/dialogs/checkbox_dialog.py

@@ -11,24 +11,24 @@ Builder.load_string('''
     pos_hint: {'top':0.9}
     BoxLayout:
         orientation: 'vertical'
-        ScrollView:
+        Widget:
-            size_hint: 1, 1
+            size_hint: 1, 0.1
         Label:
             id: description
             text: ''
-                size_hint: 1, None
             halign: 'left'
             text_size: self.width, None
+            size: self.texture_size
         BoxLayout:
             orientation: 'horizontal'
-            size_hint: 1, 0.5
+            size_hint: 1, 0.2
             Label:
                 text: _('Enable')
             CheckBox:
                 id:cb
         BoxLayout:
             orientation: 'horizontal'
-            size_hint: 1, 0.5
+            size_hint: 1, 0.2
             Button:
                 text: 'Cancel'
                 size_hint: 0.5, None