Changes the value of palette in dconf

def on_palette_color_set(self, btn):
        """Changes the value of palette in dconf
        """

        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)