Wagtail CMS color picker panel. Requires jQuery plugin http://www.eyecon.ro/colorpicker/

colorpickerpanel.py

from django.conf import settings
from django.utils.safestring import mark_safe

from wagtail.wagtailadmin.edit_handlers import BaseFieldPanel


class BaseColorFieldPanel(BaseFieldPanel):
    def render_js(self):
        big_javascript_block = """
        (function() {
          var cpjs = document.createElement('script');
          cpjs.type = 'text/javascript';
          cpjs.async = true;
          cpjs.src = '%s';
          var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(cpjs, s);

          var cpcss = document.createElement('link');
          cpcss.rel = 'stylesheet';
          cpcss.media = 'screen';
          cpcss.type = 'text/css';
          cpcss.href = '%s';
          var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(cpcss, s);

          setTimeout(function () {
            var options = {
              'onSubmit': function (a, color, c, input) {
                $(input).attr('value', '#' + color);
              },
              'onShow': function () {
                $('.colorpicker').css('z-index', 10);
              }
            }
            $('#%%s').ColorPicker(options);
          }, 3000);
        })();
        """ % (
            settings.STATIC_URL + 'js/colorpicker.js',
            settings.STATIC_URL + 'css/colorpicker.css'
        )
        return mark_safe(big_javascript_block % self.bound_field.id_for_label)


def ColorFieldPanel(field_name):
    return type(str('_ColorFieldPanel'), (BaseColorFieldPanel,), {
        'field_name': field_name,
    })

I'm trying to use this snippet with Wagtail 1.1 and is not working. "render_js" is never being called, I could not find it in BaseFieldPanel class. Have you use this code successfully sometime? Thanks!