To see AddThis blocktype in action, please visit http://mahara.ledina.org/DEV/view/view.php?id=58

Feedback appreciated.

Each iconset is contained in a folder. There must be subfolders, one for each size (at least one is expected).

E.g: Let's say we have a custom iconset, named ikone. So we create folder ikone inside htdocs/blocktype/addthis/iconsets/.
We want to add icons in different sizes, e.g.: 32px and 48px. So we create subfolders 32 and 48 inside ikone folder.
The icons of right size should go into these subfolders. The names of the files must match the service codes (that the isons represent) and the icons must be in a PNG format.

Also inside ikone folder the iconsetconfig.php file must be created and it must conatin at least:

<?php

defined('INTERNAL') || die();

$iconset = new StdClass;
$iconset->name  = 'Iconset name';
$iconset->sizes = array(32,48,64);
?>