title: how can i open a boxlayout when i press a button in kivy(i don't mean a pop up)
body: <p>I would like that to the pressure of a button in kivy is opened a boxlayout. can you please use  the kivy's propetary language.i tried this:</p>
  <pre><code>class u:
     Builder.load_string(&quot;&quot;&quot;
     &lt;Layout&gt;
         BoxLayout:
             orientation: &quot;vertical&quot;
             size: root.width, root.height
                 Button:
                     size_hint:(.2, .2)
                     font_size:32
                     text:&quot;7&quot;
                     background_color:(157/255,157/255, 157/255, 1)
                     on_press:root.x()
                         &quot;&quot;&quot;)
     def x (self):
        return Builder.load_string(&quot;&quot;&quot;
     &lt;Layout2&gt;
         BoxLayout:
             orientation: &quot;vertical&quot;
             size: root.width, root.height
                                   &quot;&quot;&quot;)
  u()
  </code></pre>