FCKeditor bugs in Dokeos implementation - the debugging process

For the sake of remembering myself of what I did, not being an expert in JavaScript coding but still needing to fix that placeholder bug in Dokeos, I'm writing this part as a real log, not really a well-presented article, but I'm still publishing it in case it would help someone else. In Dokeos, we use FCKeditor. The first problem that comes to mind is that I don't know exactly which version.

JavaScript: Image rollover

This article was first written in May 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/258).

Description

Allow to implement images rollovers by simply defining the images of a specific CSS class. Then you only have to call the function "rollover_register()" and pass it the optional parameters:
  • the CSS class you want to trigger. Default: "img.rollover".
  • the pattern you want to add to the original image (e.g.: image.png and image.over.png). Default: ".over".
  • the handler function for onMouseOver.

JavaScript: getElementsBySelector()

This article was first written in May 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/257). As of 2008, I don't
remember the source exactly, but the links will lead you to them.
Inspired by Andy, I decided to have a crack at something I've been thinking about trying for a long time. document.getElementsBySelector is a javascript function which takes a standard CSS style selector and returns an array of elements objects from the document that match that selector.

JavaScript Libraries

This article was first written in May 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/256). As of 2008, the most famous JavaScript libraries
are probably Dojo, JQuery and Prototype, but others like MeeBoo, Sarissa and Scriptaculous 
should be considered as well.

Dithered.com - Javascript Library

This is a collection of scripts that I've created and/or modified. All the scripts are released under a Creative Commons License. Do whatever you want with them - use them as is or modify them to suit your purposes.

JavaScript: Event Registration

This article was first written in May 2005 for the BeezNest technical
website (http://glasnost.beeznest.org/articles/255).

Description

Attach an event to an element by defining the type of event to listen for, the handler function to execute when the event is fired, and whether you want to use event capture.

Code

/* Author: Scott Andrew LePera (www.scottandrew.com)
Default value for useCapture has been set to false because: "If it is true,
the event listener should not fire for any element the event listener is
registered on." */
function addEvent(obj,evType