Option to limit list_filter to related_objects of instances of the list
I know there are many snippets and blog entries to do that but it is a common use case to limit the FK/related model choices to the very objects displayed in the list and maybe the core team would consider to implement it directly in the Django admin.
The +10 lines patch I provide allow you to limit the choices for a FK/M2M to the current object list by adding the attribute
RELATED_FIELD_filter_related_only=True to your ModelAdmin.
By example :
support = models.ForeignKey(Support)
parutions = models.ManyToManyField(Parution, through='OrderParution', related_name='order')
list_filter = ('support', 'agency', 'parutions')