code: def layout_filename(fallback):
      '''get location of layout file'''
      global display_size
      global vehiclename
      (dw,dh) = display_size
      if 'HOME' in os.environ:
          dirname = os.path.join(os.environ['HOME'], ".mavproxy")
          if not os.path.exists(dirname):
              try:
                  os.mkdir(dirname)
              except Exception:
                  pass
      elif 'LOCALAPPDATA' in os.environ:
          dirname = os.path.join(os.environ['LOCALAPPDATA'], "MAVProxy")
      else:
          return None
      if vehiclename:
          fname = os.path.join(dirname, "layout-%s-%ux%u" % (vehiclename,dw,dh))
          if not fallback or os.path.exists(fname):
              return fname
      return os.path.join(dirname, "layout-%ux%u" % (dw,dh)f layout_filename(fallback):
      '''get location of layout file'''
      global display_size
      global vehiclename
      (dw,dh) = display_size
      if 'HOME' in os.environ:
          dirname = os.path.join(os.environ['HOME'], ".mavproxy")
          if not os.path.exists(dirname):
              try:
                  os.mkdir(dirname)
              except Exception:
                  pass
      elif 'LOCALAPPDATA' in os.environ:
          dirname = os.path.join(os.environ['LOCALAPPDATA'], "MAVProxy")
      else:
          return None
      if vehiclename:
          fname = os.path.join(dirname, "layout-%s-%ux%u" % (vehiclename,dw,dh))
          if not fallback or os.path.exists(fname):
              return fname
      return os.path.join(dirname, "layout-%ux%u" % (dw,dh))
docs: get location of layout file