m2m_field_width_in_django_admin.py

# -*- coding: utf-8 -*-

from django.contrib import admin
from django.db import models
from django.forms import SelectMultiple
from gpdis.intranet.apps.commerce.models import Promotions, StoreAdmin

class PromotionsAdmin(admin.ModelAdmin):
    list_display = ('network', 'platform', 'start', 'end', 'source_code', 'attached_file')
    list_filter = ('platform', 'network', 'start', 'end')
    formfield_overrides = {
        models.ManyToManyField: {
            'widget': SelectMultiple(attrs={'size': '15', 'style': 'width:600px;'})
        },
    }


class StoreAdmin(admin.ModelAdmin):
    list_display = ('society', 'region', 'name', 'sign', 'main_city', 'zipcode', 'contact_email', 'visible')
    list_filter = ('region', 'sign', 'main_city', 'visible_in_list')
    search_fields = ['society', 'name', 'zipcode', 'contact_email']
    actions = ['make_visible', 'make_invisible']

    def visible(self, store):
        icon = 'tick' if store.visible_in_list else 'cross'
        return safe('<img src="{src}" />'.format(src=icon_src(icon)))
    visible.short_description = 'Visible ?'

Hmmm mec, l'air con, y'a carrément plus simple sa maman :

from django.contrib.admin.templatetags.admin_list import _boolean_icon

class SEOBlockAdmin(admin.ModelAdmin):
    list_display = ('genart', 'published', 'image_tag', 'texts_count', 'country')

    def published(self, block):
        return _boolean_icon(block.is_published)
    published.description = 'is published'