Wysywig textarea - input and "Toggle editor" button not working

[Incremental]

I have a simple Form used by Admin to reply to a Contact Form
This Admin Form has 2 Groups (Contact, Reply) and should behave like this :

• by default only the Contact Group is showed (user contact information) WITH a 'Reply' toggle button.
• clicking on the 'Reply' toggle button makes appear/dissapear the 2nd Group : Reply which contain answer fields and a button to send answer by email

Toggle 'Reply' group is working after some corrections in another post.
Now, I'm having 2 problems :

1. I have a Wysywig textarea in my Reply group. When I click on it's "Toggle editor" button, page is scrolling to top, but the editor is not compacted.
   NB : the textarea is huged compared to the values I've set in Width and Height fields.
2. I'm not able to type any text in the editor.

With Firebug, I'm getting :
NS_ERROR_UNEXPECTED:
http://www.my_test_domain.com/media/editors/tinymce/tinymce.min.js Line 4

You can see it on my test site. Log in, then Menu Fabrik / List Contacts / Edition - show 'Reply' group clicking on 'Show Reply fields' button.
Thanks by advance for help

 

[rob]

it could be an incompatibility between the slide fx and the editor. If you swap the effect on the 'show reply fields' button, over to show/hide does the issue persist?