code: def choose_meas_file(self, event=None):
          
          dlg = wx.FileDialog(
              self, message="Please choose a measurement file",
              defaultDir=self.WD,
              defaultFile="measurements.txt",
              wildcard="measurement files (*.magic,*.txt)|*.magic;*.txt",
              style=wx.FD_OPEN | wx.FD_CHANGE_DIR
          )
          if self.show_dlg(dlg) == wx.ID_OK:
              meas_file = dlg.GetPath()
              dlg.Destroy()
          else:
              meas_file = ''
              self.data_model = 2.5
              dlg.Destroy()
          return meas_file
docs: Opens a dialog allowing the user to pick a measurement file