Today, I'd like to introduce an awesome work of Japanese developers on wysiwyg editor.
"CKEditor", known as a very functional wysiwyg editor, was transplanted by Taku Amano and Toshihiro Gamou, a.k.a Dakiny.
Toshihiro Gamo, the director of CKEditor
Taku Amano of "ToI Planning", the developer of CKEditor
You can download the latest version of CKEditor from the repositry page.
Installation is very easy.
Only you have to do is unzip the file and upload them to /path/to/mt/ directory.
There are "mt-static" folder and "plugin" folder, so upload to your server all of them.
After uploading, the process of upgrade begins.
It will finish if upgrade process ends correctly.
Then you can set your own editor's configuration from "System Overview".
You can set your original css file so you can apply your website's css, then you will get a "real" screen design of your website in your CKEditor.
Addition to that, you can set this plugin to your arbitrary textarea boxes in your local blog settings.
For example, you can set CKeditor not only to your entry form, but also excerpt form, and any custom field you have created!
How do you feel?
I used it and I was really surprised by its functions.
The old version of that editor, "FCKEditor" was transplanted by great MT developer David Davis before.
This plugin was developed by the latest version of "CKEditor", so you will be satisfied with this plugin. Let's check it out!

It surprised me how elegant and configurable this plugin is. I am jealous that I cannot use it on any of my MT4 installations (I tried and failed).
The plugin is MT5 only, and I am stuck on MT4 waiting for the official update of Action Streams (personal) and MTE5 (professional).
Hi,
As you said, this "CKEditor" plugin was tuned for MT5.
For you, Taku developed "Tiny MCE" for MT4.
http://tec.toi-planning.net/en/mt/tinymce
You can download the file from here;
http://tec.toi-planning.net/en/mt/tinymce/about
http://code.google.com/p/tinymce-mtplugin/downloads/list