www programming

Yep, that's the link : http://tankistesdelombre.fr/actualites-et-infos/
You have to scroll a little before seeing it on the right (sidebar).

your widget return <li> elements that are used to display list of posts if option is for Widget without avatar.
if option would be active for avatar on widget, you should have <table> that wrap post's list.

so, you're sure that in wp_w3all config, you have activate the related option?
or you have only activate the first one
Use phpBB avatar to replace WordPress user's avatar
but NOT the necessary for widget that is immediately below:
Activate phpBB avatars on Last Forums Topics widgets

if you activate only the first option about avatars, you'll get avatars for WP posts, but not on last topic widget.

Currents Settings :

I see the first setting isset to NO.
While BOTH need to be set as YES, the first and the second.

USE phpBB avatar to replace ...
setting in your integration config page isset to NO. Set it to YES.

The BOTH need to be set as YES ?

You specififed in the settings

If this option is set to No (not active) others avatar's options Last Forums Topics widgets here below, do not affect.

??

Okey, it works.

But you have to improve the translation :p
Like :

If this option is set to No (not active) others avatar's options in Last Forums Topics widgets here below are useless, and there will be no avatars for your widget.

But 3 images / 5 aren't displaying, like a fail in the load of image ?