[Plugin: Mathtex equation editor] Missing button in frontend editor

Hello,

For educational purposes, I need to add a tinymce button in a frontend editor which enable insertion of equations for student that do not know anything about latex. In wordpress the plugin Mathtex equation editor allows this feature very well in back-end edition of posts by adding a tinymce button.

However this button do not remains on front-end edition. The frontend editor in use is defined in another plugin (Anspress). And adding ‘mathTex’ button in the following class function is apparently not sufficient.

` public function editor_buttons( $buttons, $editor_id )
{
if(is_anspress())
return array( ‘bold’, ‘italic’, ‘underline’, ‘strikethrough’, ‘bullist’, ‘numlist’, ‘link’, ‘unlink’, ‘blockquote’, ‘pre’, ‘mathTex’);

return $buttons;
}`

I have spent hours trying to figure out how to achieve this but adding filters to hook mce_external_plugins function and others do not succeeded…
Can anyone suggest me how to display this button in front-end editor also?
Thanks a lot.