Grappelli doesn't allow to extend some templates

[Alain1405]

I am trying to add an additional Save button to the admin. This can be done by extending the submit_line.html template (which is available both in Django and Grappelli templates) as documented here and here.
To be clear, I have added a template named templates/admin/app_name/model_name/submit_line.html to my project.

If I disable Grappelli the template works just fine and I see the new button. With Grappelli enabled the new template has no effect. I tried to change the order of apps without succes.

Template:

{% extends 'admin/submit_line.html' %}
{% load i18n admin_urls %}

{% block submit-row %}
    {{ block.super }}
    <NewButton>
{% endblock %}

UPDATE:
I should clarify that if I change the whole Change form template by setting change_form_template variable, then I can extend the whole form, but this is not what I want to do

[parsch]

The Grappelli submit line is not really extendable yet (it doesn't contain a block), I will take a look at that (needs different DOM and styles).

[parsch]

@Alain1405 I added a new submit line to stable/3.0.x and stable/4.0.x branches. Could you please check if that fits your purpose?

[Alain1405]

Hi @parsch , thanks for the quick response!
It looks like it works (I can extend submit_line) but the layout is now broken whether I extend the template or not.

UPDATE: I take it back, it works after refreshing the cache! Thanks for adding this, I will test a little more but looks like it's working. I checked stable/3.0.x

[parsch]

@Alain1405 thanks for checking!