While the design on the order details on the back-office is well designed on PrestaShop 1.5, the result is not good on 1.6.

You can use the structure used on the whole back-office and create a version for PS 1.6, like the module give.it did on his templates.

Availability of cURL library is not checked.
In the __construct() method you should set a warning to check if cURL is available or not.

The libraries needed by the module must be stored in the folder /lib/.

Please move timthumb.php from /img/thumb/ to /lib/ or /lib/thumb/.

UNSERIALIZE:

unserialize can lead to code execution when the data is controlled by an attacker. While it may not be trivial to control the data in the unserialize call of this module, it's still possible (through a sql injection in another module by example).

All serialize/unserialize function should be replaced with json_encode/json_decode.

Concerned files :
/clickline/clicklinecart.class.php
/clickline/clicklineorder.class.php

THIMTUMB:

The thimtumb version 2.8.13 is affected by a critical vulnerability (code execution). However the vulnerability is not exploitable when define('WEBSHOT_ENABLED') is false, which is the case in this module.

Since Thimtumb is really insecure, you should think about using another library.

We still recommand to upgrade to the latest version of thimthumb (2.8.14) and keep webshot disabled.

clickline/lib/thumb/timthumb.php

SQL:

/modules/clickline/clickline.php:769 'SELECT * FROM '.DB_PREFIX.'address where id_address = "'.$usuario_direccion_id.'"';
probably not exploitable because $params['cart'] is likely to be safe, but safer to add pSQL or intval() on $usuario_direccion_id (like you did on the others query using $usuario_direccion_id).

You can make a lot of improvements on the configuration page.

• The module must be introduced on this page. Why the merchant should use it ? How his experience can be improved by using this module ? etc.
  Here are any examples from other modules:
  
  
• The page is not easy to read and the pictures don't look beautiful when we personalize our theme with a dark configuration, as you can see on the following screen shot:
  
• Your images are disturbing. The first one just open a new tab to an external website and the second one toggle a form which could be always shown. Nothing seems to appear after these big buttons but this form, so I guess you can resize the first one, remove the second one and show immediately the configuration fields.

index.php file not found in: img/settings_options/

A confirmation message is shown when the back office configuration form is submitted, event if the form was empty.

You fixed almost everything in your penultimate commit but reverted some things in the last one.
Curly braces were placed on a new blank line but are anymore since your last commit.

Error while trying to install the module on a fresh shop install: https://www.dropbox.com/s/uqclan52ksoyf46/Capture%20d%27%C3%A9cran%202014-08-05%2014.12.25.png

https://www.dropbox.com/s/hufv1n9mxi5n6ha/Screenshot%202014-07-29%2016.30.50.png

toArray() is a method, not a function (clickline.php line 1040)

We don't really know which versions of PrestaShop are supposed to be compatible with clickline.

In the __construct(), you include the backward_compatibility to make your module compatible with PS 1.4, but then you remove it with the ps_version_compliancy between 1.5 and the last version of PS.

If clickline is compatible with 1.4, the ps_version_compliancy must be remove. If not, you can safely delete everything related to the backward_compatibility.

The use of function strtolower() is forbidden; use Tools::strtolower() instead.

• clickline.php line 554.

https://www.dropbox.com/s/9ojuhtnzw047ico/Screenshot%202014-07-29%2016.26.49.png