This option enables you to switch button and panel layout functionality. There are three diffrent layout manager options SimpleLayout that is the default layout manager, RowLayout that is the more advanced manager and finaly CustomLayout that executes a custom layout manager function. Each of these layout managers have diffrent options and can be configurated in diffrent ways. This option is only available if the advanced theme is used.
Example of usage of the theme_advanced_layout_manager option:
tinyMCE.init({ ... theme_advanced_layout_manager : "RowLayout" });