code: def on_palette_color_set(self, btn):
          
  
          palette = []
          for i in range(18):
              palette.append(hexify_color(self.get_widget('palette_%d' % i).get_color()))
          palette = ':'.join(palette)
          self.settings.styleFont.set_string('palette', palette)
          self.settings.styleFont.set_string('palette-name', _('Custom'))
          self.set_palette_name('Custom')
          self.update_demo_palette(palette)
docs: Changes the value of palette in dconf