This option should contain a comma separated list of supported browsers. This enables you to for example disable the editor while running on Safari. The default value of this option is: msie,gecko,safari,opera and since the support for Safari is very limited a warning message will appear until a better version is released. The possible values of this option is msie, gecko and safari.
Example of usage of the browsers option:
tinyMCE.init({ ... browsers : "msie,gecko,opera" });