docs: def Build_ConfigPanel(self):
          """config panel for left-hand-side of frame: RGB Maps"""
          panel = self.config_panel
          sizer = wx.BoxSizer(wx.VERTICAL)
  
          lsty = wx.ALIGN_LEFT|wx.LEFT|wx.TOP|wx.EXPAND
  
          if self.config_mode == 'rgb':
              for icol, col in enumerate(RGB_COLORS):
                  self.cmap_panels[icol] =  ColorMapPanel(self.config_panel,
                                                         self.panel,
                                                         title='%s: ' % col.title(),
                                                         color=icol,
                                                         default=col,
                                                         colormap_list=None)
  
                  sizer.Add(self.cmap_panels[icol], 0, lsty, 2)
  
                  sizer.Add(wx.StaticLine(self.config_panel, size=(100, 2),
                                          style=wx.LI_HORIZONTAL), 0, lsty, 2)
  
              self.interp_panel = InterpPanel(self.config_panel,
                                              callback=self.onInterp)
              self.contrast_panel = ContrastPanel(self.config_panel,
                                              callback=self.set_contrast_levels)
  
              sizer.Add(self.interp_panel, 0, lsty, 2)
              sizer.Add(self.contrast_panel, 0, lsty, 2)
  
  
          else:
              self.cmap_panels[0] =  ColorMapPanel(self.config_panel,
                                                   self.panel,
                                                   default='gray',
                                                   colormap_list=ColorMap_List)
              self.interp_panel = InterpPanel(self.config_panel,
                                              callback=self.onInterp)
              self.contrast_panel = ContrastPanel(self.config_panel,
                                              callback=self.set_contrast_levels)
  
              sizer.Add(self.cmap_panels[0],  0, lsty, 1)
              sizer.Add(wx.StaticLine(self.config_panel, size=(100, 2),
                                      style=wx.LI_HORIZONTAL), 0, lsty, 2)
              sizer.Add(self.interp_panel, 0, lsty, 2)
              sizer.Add(self.contrast_panel, 0, lsty, 2)
  
          cust = self.CustomConfig(self.config_panel, None, 0)
          if cust is not None:
              sizer.Add(cust, 0, lsty, 1)
          pack(self.config_panel, sizer)