As so many languages in the world have right to left(RTL) directionality instead of LTR(Like persian, arabic, urdo, pashtu,...) , it's vital to implement tinyMCE directionality plugin into wordpress, As wordpress uses gzip compression for loading TinyMCE and because required plugins most be set before init,
<script language="javascript" type="text/javascript"
src="../wp-includes/js/tinymce/tiny_mce_gzip.php?
index=0&theme=advanced
&plugins=wordpress,autosave,wphelp">
</script>
it's impossible to do this task with plugins (through mce_options action hook) so these changes most be made to wordpress admin-header.php in order to activate LTR/RTL buttons in TinyMCE.
important note: Directionality plugin folder (10.1KB) also needed in order to LTR/RTL implementation, Those files are included in standard tinyMCE release and most be copied to wp-includes\js\tinymce\plugins
more info about the plugin: http://tinymce.moxiecode.com/tinymce/docs/plugin_directionality.html
