admin.py

from django.contrib.auth.admin import UserAdmin, GroupAdmin
from django.contrib.auth.models import Permission, Group
from django.utils.translation import ugettext, ugettext_lazy as _

from django.forms import ModelForm
from django.db.models import Q


# editando el users admin.

UserAdmin.filter_horizontal = ("groups","")
UserAdmin.fieldsets = (
              (None, {'fields': ('username', 'password')}),
              (_('Personal info'), {'fields': ('first_name', 'last_name', 'email')}),
              (_('Permissions'), {'fields': ('is_active', 'is_staff', 'is_superuser')}),
              (_('Important dates'), {'fields': ('last_login', 'date_joined')}),
              (_('Groups'), {'fields': ('groups',)}),
          )
UserAdmin.exclude = ("user_permissions","")


# filtrando el admin de Groups

class GroupForm(ModelForm):
    class Meta:
        model = Group
    def __init__(self,*args,**kwargs):
        super(GroupForm,self).__init__(*args,**kwargs)
        perms = Permission.objects.filter(
               Q( content_type__app_label__contains = 'guias')|
                Q(content_type__app_label__contains = 'evento')
        )
        perms_list = [ (obj.id, obj.__unicode__()) for obj in perms]
        self.fields["permissions"].widget.choices = perms_list
GroupAdmin.form = GroupForm