This option enables you to specify what theme to use when rendering the TinyMCE WYSIWYG editor instances. This name matches the directories located in "tinymce/jscripts/tiny_mce/themes". The default value of this option is "advanced". TinyMCE has three built in themes and these are described in greater detail below.
advanced
This is the advanced theme of TinyMCE, this theme enables users to add/remove buttons and panels and is a lot more flexible than the simple or default theme. For more information about this themes specific options check the "Advanced theme" configuration section.
simple
This is the most simple theme for TinyMCE it contains only the basic functions.Example of usage of the theme option:
tinyMCE.init({
...
theme : "advanced",
theme_advanced_buttons3_add_before : "tablecontrols,separator"
});