It's possible to add new editors to Moodle and replace or augment TinyMCE.
Add a new Editor to Moodle
The editor is a plugin used by Moodle that we can find in the Moodle source files folowing the path /lib/editor/
Moodle tipically uses the TinyMCE editor, but other editors can be installed in Moodle.
We can find other editors that can be installed in Moodle.
Specific Moodle TinyMCE plugins can be created in order to augment TinyMCE functionalities.
Here you will find some tips of how to create your own button, a Moodle specific TinyMCE plugin.
TODO: Finish this page.