code: def OnOpenFile(self, event):
          
          dialog = wx.FileDialog(self, style=wx.OPEN|wx.FD_MULTIPLE)
          if dialog.ShowModal() == wx.ID_OK:
              paths = dialog.GetPaths()
              if self.loader:
                  # we've already got a displayed data-set, open new window...
                  frame = MainFrame()
                  frame.Show(True)
                  frame.load(*paths)
              else:
                  self.load(*paths)
docs: Request to open a new profile file