title: Kivy Dropdown always selects the same text no matter which option is selected
body: <p>Trying to implement two dropdowns in kivy. The buttons are added to the dropdown from two dictionaries. However, no matter which option is clicked, the final entry in the two dictionaries is actually selected.</p>
  <p>Here's the relevant code:</p>
  <pre><code>elf.authProtocols = {
          'None' : usmNoAuthProtocol,
          'MD5' : usmHMACMD5AuthProtocol,
          'SHAv1' : usmHMACSHAAuthProtocol,
          'SHAv2 224bit' : usmHMAC128SHA224AuthProtocol,
          'SHAv2 256bit' : usmHMAC192SHA256AuthProtocol,
          'SHAv2 384bit' : usmHMAC256SHA384AuthProtocol,
          'SHAv2 512bit' : usmHMAC384SHA512AuthProtocol
          }
  
          self.privProtocols = {
          'None' : usmNoPrivProtocol,
          'DES' : usmDESPrivProtocol,
          '3DES' : usm3DESEDEPrivProtocol,
          'AES 128bit' : usmAesCfb128Protocol,
          'AES 192bit' : usmAesCfb192Protocol,
          'AES 256bit' : usmAesCfb256Protocol
          }
  
  (Other code here)
  
  #The dropdown for selecting the authentication protocol
          self.authProtocolDropdown = DropDown()
          #Iterate over the protocols and add our buttons to the list   
          for x in self.authProtocols:
              btn = Button(text='{0}'.format(x),
                  size_hint_y=None, height=24, width = 128)
              btn.bind(on_release=lambda btnAuth: 
                  self.authProtocolDropdown.select(btn.text))
              self.authProtocolDropdown.add_widget(btn)
          
          #This is the button that opens the dropdown
          authProtocolButton = Button(text ='Auth Protocols', size_hint =(None, None),
               width = 700, height = 36)
          authProtocolButton.bind(on_release = self.authProtocolDropdown.open)
          self.authProtocolDropdown.bind(on_select=lambda instanceAuth,
               x : setattr(authProtocolButton, 'text', x))
  
          #The dropdown for selecting the encryption (priv) protocol
          self.privProtocolDropdown = DropDown()
          #Iterate over the protocols and add our buttons to the list   
          for x in self.privProtocols:
              btn = Button(text='{0}'.format(x),
                  size_hint_y=None, height=24, width = 128)
              btn.bind(on_release=lambda btnPriv: self.privProtocolDropdown.select(x))
              self.privProtocolDropdown.add_widget(btn)
          
          #This is the button that opens the dropdown
          privProtocolButton = Button(text ='Priv Protocols', size_hint =(None, None),
               width = 700, height = 36)
          privProtocolButton.bind(on_release = self.privProtocolDropdown.open)
          self.privProtocolDropdown.bind(on_select=lambda instancePriv,
               x: setattr(privProtocolButton, 'text', x))
  </code></pre>
  <p>I'm sure there's something quite obvious I'm missing, this is my first kivy project.</p>
  <p>Examples:</p>
  <p>[Dropdown menu]<br />
  <img src="https://i.stack.imgur.com/1bgdp.png" alt="1" /></p>
  <p>[AES 256 is always selected no matter which option is clicked]<br />
  <img src="https://i.stack.imgur.com/FYD7U.png" alt="2" /></p>