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)