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.