After install remember to change your default editor to "Editor Switcher" in your admin configuration page.
Enabling the editor and then visiting an article in the administrator site, PHP will fatal-quit because it requires(!) a php-file within the editor switcher directory named like the installed editors.
A quick peek at the code shows it iterating over all installed editor-plugins and require_once()-ing a plg-local file.
Thus, the downloadable package seems 1.) incomplete, 2.) untested.
I also question the concept being used here in general. It means the editor-switcher would require a PHP file for each editor you install. And it will not be able to provide these for custom installed editors or custom editors.
I want you for me to help for a GPL license.
Of course, although I am testing, it cannot test in the environment which I do not know.
Then, please tell me the editor which you have installed, and environment.
In addition, it is only the selected editor that is requiring.
The only problem is there's absolutely no documentation. It took me some time to figure that I need to set my default editor to "Editor switcher". I though a button would appear on the bottom of the editor.
1) you have to be aware that besides editing the plugin configuration you must also edit each user profile that you wish to have the button.
2) an odd arrangement of additional ACL must be configured inside the plug-in. (The odd part is that this is confusing and perhaps redundant).
But on the whole this adds a great efficiency and usability boost to Joomla editing. Fantastic!