new_contents: from django import forms
  from django.template import Context, Template
  
  class ProductImageMultipleChoiceField(forms.ModelMultipleChoiceField):
      """
      Field that renders a ProductImage as a thumbnail and text instead of
      just as text.
      """
  
      # Using the low-level Template API instead of storing it in a separate file
      # A user might want to override this, so perhaps it should be a 'partial' template
      _template = Template("""
      {% load thumbnail %}
      
      {% thumbnail image.original "50x50" crop="center" as thumb %}
      <img src="{{ thumb.url }}" alt="{{ image }}" /> {{ image.original }}
      {% endthumbnail %}
      """)
  
  
      def __init__(self, *args, **kwargs):
          if 'widget' not in kwargs:
              kwargs['widget'] = forms.CheckboxSelectMultiple()
  
          if 'required' not in kwargs:
              kwargs['required'] = False
  
          super(ProductImageMultipleChoiceField, self).__init__(*args, **kwargs)
  
      def label_from_instance(self, obj):
          return self._template.render(Context({
              'image': obj
          }))
subject: Add field to render image many-to-many as checkboxes with thumbnails.